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Observe the motions of Venus and Earth as the planets move around the Sun. Measure the length of a day and a year on Earth and Venus, and compare the length of a solar day to the length of a sidereal day.

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Observe the motions of the Earth, Moon and Sun in three dimensions to explain Sunrise and Sunset, and to see how we define a day, a month, and a year. Compare times of Sunrise and Sunset for different dates and locations. Relate shadows to the position of the Sun in the sky, and relate shadows to compass directions.

Lake City's latest heat wave has more people in the hospital than ever before. Juan, a local student admitted to the hospital, lives in one of the hottest neighborhoods in the city. Students are hired as the city's Chief Heat Officer to investigate and solve the problem. As the Chief Heat Officer, students look at land uses, surface air temperatures, and building materials across Lake City. Students will develop a system model to test several design solutions and give the mayor a proposal to beat the heat.

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Observe solar and lunar eclipses as the Moon orbits Earth. The full and partial shadows of the Moon and Earth can be displayed, and the Moon can also be dragged around Earth. See what the Moon and Sun look like from Earth during partial and total eclipses.

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Understand the phases of the Moon by observing the positions of the Moon, Earth and Sun. A view of the Moon from Earth is shown on the right as the Moon orbits Earth. Learn the names of Moon phases and in what order they occur. Click Play to watch the Moon go around, or click Pause and drag the Moon yourself.

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Observe the tilt of Earth's axis and the angle that sunlight strikes Earth on June 21 and December 21. Compare day lengths, temperatures, and the angle of the Sun's rays for any latitude. The tilt of the Earth's axis can be varied to see how this would affect seasons.

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Gain an understanding of moonrise and moonset times by observing the relative positions of Earth and the Moon along with a view of the Moon from Earth. A line shows the horizon for a person standing on Earth so that moonrise and moonset times can be determined.

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Apply ratios and proportions to find the weight of a person on the moon (or on another planet). Weigh an object on Earth and on the moon and weigh the person on Earth. Then set up and solve the proportion of the Earth weights to the moon weights.

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Apply ratios and proportions to find the weight of a person on the moon (or on another planet). Weigh an object on Earth and on the moon and weigh the person on Earth. Then set up and solve the proportion of the Earth weights to the moon weights.

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The Coriolis effect causes winds to be deflected as they move across Earth's surface, resulting in circular patterns of winds. This effect is caused by two factors, Earth's rotation and frame of reference. In the Coriolis Effect Gizmo, students will build their understanding of this phenomenon using the analogy of two kids playing catch: first on a train, then on a merry-go-round, and finally on Earth's surface.

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Observe the motions of the Earth, Moon and Sun in three dimensions to investigate the causes and frequency of eclipses. Observe Earth's shadow crossing the Moon during a lunar eclipse, and the path of the Moon's shadow across Earth's surface during a solar eclipse. The angle of the Moon's orbit can be adjusted, as well as the distance of the Moon from the Earth.

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Find the effect of length, mass, and angle on the period of a pendulum. The pendulum is attached to a clock that can be adjusted to tell time accurately. The clock can be located on Earth or Jupiter to determine the effect of gravity.

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Learn why the temperature in the summertime is higher than it is in the winter by studying the amount of light striking the Earth. Experiment with a plate detector to measure the amount of light striking the plate as the angle of the plate is adjusted (and then use a group of plates placed at different locations on the Earth) and measure the incoming radiation on each plate.

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Use a balance to measure mass and a spring scale to measure the weight of objects. Compare the masses and weights of objects on Earth, Mars, Jupiter, and the Moon.

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Move the Earth's crust at various locations to observe the effects of the motion of the tectonic plates, including volcanic eruptions. Information about each of the major types of plate boundaries is shown, along with their locations on Earth.

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Manipulate the position of the Moon to model solar and lunar eclipses. View Earth's shadow, the Moon's shadow, or both. Observe the Moon and Sun from Earth during a partial and total eclipse. The sizes of the three bodies and the Earth-Moon distance can be adjusted.

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Gain an understanding of high, low, spring, and neap tides on Earth by observing the tidal heights and the positions of the Earth, Moon, and Sun. Tidal bulges can be observed from space, and water depths can be recorded from a dock by the ocean.

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Gain an understanding of high, low, spring, and neap tides on Earth by observing the tidal heights and the position of the Earth, Moon, and Sun. Tidal bulges can be observed from space, and water depths can be recorded from a dock by the ocean.

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Develop an understanding of ocean tides by comparing the depth of water near a dock to the positions of the Moon, Sun, and Earth. Determine the influence of the Moon and Sun on tides, and compare spring tides to neap tides.

The Bay Area of California experiences frequent earthquakes. Earthquakes are unpredictable and cause enormous damage that leads to casualties. Students take on the role of an earth scientist to investigate the properties of seismic waves to develop an early warning system that warns citizens of an incoming earthquake and reduces casualties.

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In 1915, Alfred Wegener proposed that all of Earth's continents were once joined in an ancient supercontinent he called Pangaea. Wegener's idea of moving continents led to the modern theory of plate tectonics. Create your own version of Pangaea by fitting Earth's landmasses together like puzzle pieces. Use evidence from fossils, rocks, and glaciers to refine your map.

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Play the role of a piece of rock moving through the rock cycle. Select a starting location and follow many possible paths throughout the cycle. Learn how rocks are formed, weathered, eroded, and reformed as they move from Earth's surface to locations deep within the crust.

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Use a three dimensional view of the Earth, Moon and Sun to explore seasonal changes at a variety of locations. Strengthen your knowledge of global climate patterns by comparing solar energy input at the Poles to the Equator. Manipulate Earth's axis to increase or diminish seasonal changes.

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Use a sonar on a boat to remotely measure the depth of an ocean at various locations. Describe multiple points on the ocean floor using their latitude, longitude, and depth. View maps of ocean depth in two and three dimensions, and use these maps to plot a safe route for ships to follow.

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Explore our solar system and learn the characteristics of each planet. Compare the sizes of planets and their distances from the Sun. Observe the speeds of planetary orbits and measure how long each planet takes to go around the Sun.

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Gain an understanding of the causes of seasons by observing Earth as it orbits the Sun in three dimensions. Observe the path of the Sun across the sky on any date and from any location. Create graphs of solar intensity and day length, and use collected data to describe and explain seasonal changes.

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Measure the strength and direction of the magnetic field at different locations in a laboratory. Compare the strength of the induced magnetic field to Earth's magnetic field. The direction and magnitude of the inducting current can be adjusted.

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Learn about standard symbols used in meteorology to construct weather maps. Rain, sleet, snow, temperature, cloud cover, wind speed and direction, and atmospheric pressure can all be recorded at two different weather stations on a map. Describe weather patterns characteristic of high-pressure systems, low-pressure systems, warm fronts, and cold fronts.

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Observe daily weather conditions in a coastal region. Measure temperatures and wind speeds at any location and use this data to map convection currents that form during the day and night. Explain the origin of land breezes and sea breezes.

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Survey the solar system, observing the length of a year and the orbital path of each object. The positions of the eight official planets are displayed, as well as one dwarf planet, Pluto. Learn about Kepler's Laws and how planets are classified.

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You are a bird hunting moths (both dark and light) that live on trees. As you capture the moths most easily visible against the tree surface, the moth populations change, illustrating the effects of natural selection.

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Drag blocks onto a two-dimensional surface and observe the effects on the center of mass. Use a grid to calculate the coordinates of the center of mass. Investigate predefined shapes or your own arrangements of blocks.

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Learn about standard symbols used in meteorology to construct weather maps. Rain, sleet, snow, temperature, cloud cover, wind speed and direction, and atmospheric pressure can all be recorded at two different weather stations on a map. Describe weather patterns characteristic of high-pressure systems, low-pressure systems, warm fronts, and cold fronts.

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Observe daily weather conditions in a coastal region. Measure temperatures and wind speeds at any location and use this data to map convection currents that form during the day and night. Explain the origin of land breezes and sea breezes.

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Build a home to survive a flood or a hurricane and protect the people inside. Choose materials and a design for the foundation, frame, walls, and roof of the house. Add "extras" such as sand bags, storm shutters, and roof clips. Test your house in a flood or storm and see how well your design worked.

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Weathering is the breakdown of rock at Earth's surface through physical or chemical means. Students will learn about the different types of mechanical and chemical weathering, then use a simulation to model the effects of weathering on different types of rocks in varying climate conditions.

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Fold paper and cut in a certain way to make symmetrical snowflakes with six sides (similar to what can be found in nature) or with eight sides (an easier folding method). This simulation allows you to cut virtual paper on the computer screen with round dot or square dot "scissors" of various sizes before using physical paper.

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Imagine a gigantic pitcher standing on Earth, ready to hurl a huge baseball. What will happen as the ball is thrown harder and harder? Find out with the Gravity Pitch Gizmo. Observe the path of the ball when it is thrown at different velocities. Throw the ball on different planets to see how each planet's gravity affects the ball.

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Control the temperature of a beaker of water. As the temperature drops below the freezing point, a transformation of state will occur that can be viewed on a molecular level. Salt can be added to the water to see its effect on the freezing point of water.

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Try to classify a dozen different rock samples based on their appearance. Common characteristics of each major rock type are described. Rocks also can be classified by where they formed.

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Get to know the four main types of pollution present in the environment, and then look at a variety of real-world examples as you try to guess what type of pollution is represented by each situation. All of the real-world situations can be viewed every day in different parts of the world.

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Explore the energy used by many household appliances, such as television sets, hair dryers, lights, computers, etc. Make estimates for how long each item is used on a daily basis to get an estimate for the total power consumed during a day, a week, a month, and a year, and how that relates to consumer costs and environmental impact.

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Analyze the spectra of a variety of stars. Determine the elements that are represented in each spectrum, and use this information to infer the temperature and classification of the star. Look for unusual features such as redshifted stars, nebulae, and stars with large planets.

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Learn Kepler's three laws of planetary motion by examining the orbit of a planet around a star. The initial position, velocity, and mass of the planet can be varied as well as the mass of the star. The foci and centers of orbits can be displayed and compared to the location of the star. The area swept out by the planet in a given time period can be measured, and data on orbital radii and periods can be plotted in several ways.

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Design a house to withstand an earthquake and protect the people living inside. Select a location in San Francisco, then choose the design and materials for a foundation, frame, walls, and roof. Decide which extras to add to your home design. Test each house in an earthquake and assess the damages. Try to arrive at a house design that results in the least damage.

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Within this simulated region of land, daytime's rising temperature and the falling temperature at night can be measured, along with heat flow in and out of the system. The level of greenhouse gases present in the atmosphere at any given time can be adjusted, allowing the long-term effects to be investigated.

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Pour water on a variety of sediment samples to find how much water can be absorbed by the sample (porosity) and how easily water flows through the sample (permeability).

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Within this simulated region of land, daytime's rising temperature and the falling temperature at night can be measured, along with heat flow in and out of the system. The amount of greenhouse gases present in the atmosphere can be adjusted through time, and the long-term effects can be investigated.

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A collection of stars visible from Earth can be arranged and classified based on their color, temperature, luminosity, radius, and mass. This can be done using one or two-dimensional plots, including a Hertzsprung-Russell diagram of luminosity vs. temperature.

Is this plastic cup sustainable? As a plastics engineer, the student must create a plastic cup from renewable resources that returns its material to Earth’s carbon cycle through decomposition by living things.

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Use data from up to three weather stations to predict the motion of a hurricane. The wind speed, wind direction, cloud cover and air pressure are provided for each station using standard weather symbols.

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Understand how topographic maps work by creating a three-dimensional landscape and observing the corresponding contour lines. See how mountains, depressions, valleys and cliffs are represented on topographic maps. Fill in the landscape with water to demonstrate that contours are lines of constant elevation.

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Use data from up to three weather stations to predict the motion of a hurricane. The wind speed, wind direction, cloud cover and air pressure are provided for each station using standard weather symbols.

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Observe and measure the properties of a mineral sample, and then use a key to identify the mineral. Students can observe the color, luster, shape, density, hardness, streak, and reaction to acid for each mineral. There are 26 mineral samples to identify.

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Measure the temperature on wet and dry bulb thermometers to determine relative humidity. Measure the dew point by cooling a bucket of water until condensation forms on the surface. See how the relative humidity and dew point change over the course of a day.

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Observe the partial shadows cast by a rectangular block lit by multiple light sources. The number of light sources ranges from one to five, and individual lights can be turned on or off. The light spacing, block width, and distance from the lights to the block can be varied. Light intensity can be observed on a detector.

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Build a topographic map by flooding a three dimensional landscape with water and drawing contour lines. Draw a profile of a landscape based on the topographic map.

Students acting as spacecraft navigation engineers apply their knowledge of Newton’s Third Law of Motion to launch a communication satellite into a stable orbit around Earth. When students learn of an impending collision with space debris, they must use their knowledge of gravitational forces and Newton’s Laws to correctly maneuver their satellite to a new, stable orbit.

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Explore the causes of convection by heating liquid and observing the resulting motion. The location and intensity of the heat source (or sources) can be varied, as well as the viscosity of the liquid. Use a probe to measure temperature and density in different areas and observe the motion of molecules in the liquid. Then, explore real-world examples of convection cells in Earth's mantle, oceans, and atmosphere.

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You are the captain of an interplanetary cargo ship, delivering important supplies to the outer planets. The cargo can be stored in barrels, crates, and holds. (There are 10 barrels in a crate, and 10 crates in a hold.) Model multi-digit subtraction by unloading cargo on each planet.

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Control the path of a drop of water as it travels through the water cycle. Many alternatives are presented at each stage. Determine how the water moves from one location to another, and learn how water resources are distributed in these locations.

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Use the Unit Conversions Gizmo to explore the concepts of scientific notation and significant digits. Convert numbers to and from scientific notation. Determine the number of significant digits in a measured value and in a calculation.

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Adjust the mass and velocity of two gliders on a frictionless air track. Measure the velocity, momentum, and kinetic energy of each glider as they approach each other and collide. Collisions can be elastic or inelastic.

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Investigate the energy and motion of a block sliding down an inclined plane, with or without friction. The ramp angle can be varied and a variety of materials for the block and ramp can be used. Potential and kinetic energy are reported as the block slides down the ramp. Two experiments can be run simultaneously to compare results as factors are varied.

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Add varying amounts of a chemical to a beaker of water to create a solution, observe that the chemical dissolves in the water at first, and then measure the concentration of the solution at the saturation point. Either potassium nitrate or sodium chloride can be added to the water, and the temperature of the water can be adjusted.

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Using four beakers of liquids with known densities, estimate the density of a variety of objects. Place each object into each beaker to see whether it sinks or floats, and then use this information to compare the densities of the objects.

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Using the scientific method, control the environmental conditions for a fictional alien organism in order to learn how the organism responds to changes in conditions. Sunlight, water, and temperature can be varied to determine their effects on the shape of the aliens.

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Control the intensity of red, green, and blue spotlights. Additive colors can be observed where the spotlights overlap. The RGB value of any point can be measured. Just about any color can be created by mixing varying amounts of red, green, and blue light.

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Point a laser at a mirror and compare the angle of the incoming beam to the angle of reflection. A protractor can be used to measure the angles of incidence and reflection, and the angle of the mirror can be adjusted. A beam splitter can be used to split the beam. Both plane and irregular mirrors can be used.

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Measure the position, velocity, and acceleration (both components and magnitude) of an object undergoing circular motion. The radius and velocity of the object can be controlled, along with the mass of the object. The forces acting on the object also can be recorded.

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Test the acidity of common substances using pH paper. Materials including soap, lemon juice, milk, and oven cleaner can be tested by comparing the color of pH strips to a standard scale.

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Test the acidity of many common everyday substances using pH paper (four color indicators). Materials including soap, lemon juice, milk, and oven cleaner can be tested by comparing the color of the pH strips to the calibrated scale.

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Observe the sex ratios of birds and geckos as they hatch in an incubator. Vary the temperature of the incubator and measure the percentages of male and female hatchlings to determine if temperature has an effect on sex.

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Adjust the hills on a toy-car roller coaster and watch what happens as the car careens toward an egg (that can be broken) at the end of the track. The heights of three hills can be manipulated, along with the mass of the car and the friction of the track. A graph of various variables of motion can be viewed as the car travels, including position, speed, acceleration, potential energy, kinetic energy, and total energy.

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Scan the DNA of frogs to produce DNA sequences. Use the DNA sequences to identify possible identical twins and to determine which sections of DNA code for skin color, eye color, and the presence or absence of spots.

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Place a pan on the end of a hanging spring. Measure how much the spring stretches when various masses are added to the pan. Create a graph of displacement vs. mass to determine the spring constant of the spring.

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Pith balls with positive, negative, or no electrical charge are suspended from strings. The charge and mass of the pith balls can be adjusted, along with the length of the string, which will cause the pith balls to change position. Distances can be measured as variables are adjusted, and the forces (Coulomb and gravitational) acting on the balls can be displayed.

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Use a pulley system to lift a heavy weight to a certain height. Measure the force required to lift the weight using up to three fixed and three movable pulleys. The weight to be lifted and the efficiency of the pulley system can be adjusted, and the height of the weight and the total input distance are reported.

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Observe the sex ratios of birds and geckos as they hatch in an incubator. Vary the temperature of the incubator and measure the percentages of male and female hatchlings to determine if temperature has an effect on sex.

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Drag bar magnets and a variety of other objects onto a piece of paper. Click Play to release the objects to see if they are attracted together, repelled apart, or unaffected. You can also sprinkle iron filings over the magnets and other objects to view the magnetic field lines that are produced.

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Observe the steps of pollination and fertilization in flowering plants. Help with many parts of the process by dragging pollen grains to the stigma, dragging sperm to the ovules, and removing petals as the fruit begins to grow. Quiz yourself when you are done by dragging vocabulary words to the correct plant structure.

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Observe frogs jumping around on colored lily pads. Find, test, and reason about patterns you see in their jumping.

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Observe and measure transverse, longitudinal, and combined waves on a model of a spring moved by a hand. Adjust the amplitude and frequency of the hand, and the tension and density of the spring. The speed and power of the waves is reported, and the wavelength and amplitude can be measured.

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Observe the spread of disease through a group of people. The methods of transmission can be chosen and include person-to-person, airborne, and foodborne as well as any combination thereof. The probability of each form of transmission and number of people in the group can also be adjusted.

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Study the thickness of birds' beaks over a five-year period as you control the yearly rainfall on an isolated island. As the environmental conditions change, the species must adapt (a real-world consequence) to avoid extinction.

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Move spots of yellow, cyan, and magenta pigment on a white surface. As the colors overlap, other colors can be seen due to color subtraction. The color of most things you see--such as cars, leaves, paintings, houses, and clothes--are due to color subtraction. The intensity of the cyan, magenta, and yellow can be adjusted, and the RGB value at any location can be measured.

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Label a diagram that illustrates the anatomy of a flower, and understand the function of each structure. Compare the processes of self pollination and cross pollination, and explore how fertilization takes place in a flowering plant.

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Solve problems in chemistry using dimensional analysis. Select appropriate tiles so that units in the question are converted into units of the answer. Tiles can be flipped, and answers can be calculated once the appropriate unit conversions have been applied.

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Set the initial percentages of three types of parrots in a population and track changes in genotype and allele frequency through several generations. Analyze population data to develop an understanding of the Hardy-Weinberg equilibrium. Determine how initial allele percentages will affect the equilibrium state of the population.

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Derive an equation to calculate the frequency of an oncoming sound source and a receding sound source. Also, calculate the Doppler shift that results from a moving observer and a stationary sound source. The source velocity, sound velocity, observer velocity, and sound frequency can all be manipulated.

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Observe light rays that reflect from a convex or concave mirror. Manipulate the position of an object and the focal length of the mirror and measure the distance and size of the resulting image.

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Investigate the growth of three common garden plants: tomatoes, beans, and turnips. You can change the amount of light each plant gets, the amount of water added each day, and the type of soil the seed is planted in. Observe the effect of each variable on plant height, plant mass, leaf color and leaf size. Determine what conditions produce the tallest and healthiest plants. Height and mass data are displayed on tables and graphs.

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Plant seeds and watch how many sprout. Examine what factors affect germination. Vary the amount of heat, water, and light the seeds get. Practice designing controlled experiments and using the scientific method.

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Use a lever to lift a pig, turkey, or sheep. A strongman provides up to 1000 newtons of effort. The fulcrum, strongman, and animals can be moved to any position to create first-, second-, or third-class levers.

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Lift food using ants with the help of a slanted stick. The steepness of the stick, the number of ants, and the size of the item being lifted can be varied. Observe the effect of friction on sliding objects.

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Use a wheel and axle to move a heavy load. Find out how many athletes it takes to move the load under different conditions. The radii of the wheel and the axle can be adjusted to help study mechanical advantage.

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Use a powerful flashlight to pop a kernel of popcorn. A lens focuses light on the kernel. The temperature of the filament and the distance between the flashlight and lens can be changed. Several obstacles can be placed between the flashlight and the popcorn.

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Investigate how an inclined plane redirects and reduces the force pulling a brick downward, with or without friction. A toy car can apply a variable upward force on the brick, and the mechanical advantage and efficiency of the plane can be determined. A graph of force versus distance illustrates the concept of work.

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Create molecules using building blocks of carbon, hydrogen, oxygen, nitrogen, and other elements. Connect atoms by bonds, then create double or triple bonds if desired. For each completed molecule, write the chemical formula and, if the molecule is included in the database, observe the 3D structure. Create a variety of challenge molecules including cyclic molecules and isomers.

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Observe how photoreceptors on the retina are stimulated by different colors of light. Determine that cone cells are stimulated by specific colors of light and enable us to see color, while rod cells are stimulated by various colors and do not contribute to color vision. Experiment by varying the percentage of rod and cone cells in normal and dim light to see how rod cells help with night vision.

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Once light enters the eye, it must be focused on the retina. Manipulate the pupil diameter to regulate the amount of light that enters then eye, then change the lens shape to focus light. Determine the changes in lens shape needed to maintain focus as the object distance changes. This is a followup to the Eyes and Vision 1 - Seeing Colors lesson.

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Collect fingerprints from simulated crime scenes using a camera, fingerprinting powder, and tape. Classify fingerprints into groups and subgroups, then identify minutiae. Match collected prints to the fingerprints of suspects to identify who left prints at the scene of the crime.

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Explore relationships between amount, temperature, pressure, and volume for an ideal gas in a chamber with a moveable piston. Discover rules of proportionality contained in Boyle's law, Charles's law, Avogadro's law, and Gay-Lussac's law. Use these relationships to derive the ideal gas law and calculate the value of the ideal gas constant.

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Observe how different colors of light are reflected or absorbed by colored objects. Determine that white light is a combination of different colors of light, and that one or more component colors may be reflected when white light is shone on an object. Understand that we see an object when light reflected from the object enters our eye.

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Learn about molecular polarity and how polarity gives rise to intermolecular forces. Measure four macroscopic properties of liquids (cohesion, adhesion, surface tension, and capillary rise). Compare these properties for different liquids and relate them to whether the substances are polar or nonpolar.

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Explore erosion in a simulated 3D environment. Observe how the landscape evolves over time as it is shaped by the forces of flowing water. Vary the initial landscape, rock type, precipitation amount, average temperature, and vegetation and measure how each variable affects the rate of erosion and resulting landscape features.

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Study wave motion, diffraction, interference, and refraction in a simulated ripple tank. A wide variety of scenarios can be chosen, including barriers with one or two gaps, multiple wave sources, reflecting barriers, or submerged rocks. The wavelength and strength of waves can be adjusted, as well as the amount of damping in the tank.

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Explore how a changing magnetic field can induce an electric current. A magnet can be moved up or down at a constant velocity below a loop of wire, or the loop of wire may be dragged in any direction or rotated. The magnetic and electric fields can be displayed, as well as the magnetic flux and the current in the wire.

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Measure the quantity of a known solution needed to neutralize an acid or base of unknown concentration. Use this information to calculate the unknown concentration. A variety of indicators can be used to show the pH of the solution.

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Observe how reactants and products interact in reversible reactions. The initial amount of each substance can be manipulated, as well as the pressure on the chamber. The amounts, concentrations, and partial pressures of each reactant and product can be tracked over time as the reaction proceeds toward equilibrium.

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Use dichotomous keys to identify and classify five types of organisms: California albatrosses, Canadian Rockies buttercups, Texas venomous snakes, Virginia evergreens, and Florida cartilagenous fishes. After you have classified every organism, try making your own dichotomous key!

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Observe how reactants and products interact in reversible reactions. The amounts of each substance can be manipulated, as well as the pressure on the chamber. This lesson focuses on partial pressures, Dalton's law, and Le Chatelier's principle.

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Design your own trebuchet to fling a projectile at a castle wall. All of the dimensions of the trebuchet can be adjusted, as well as the masses of the counterweight and payload. Select a target on the Launch tab, or just see how far your projectile will go.

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Exothermic chemical reactions release energy, while endothermic reactions absorb energy. But what causes some reactions to be exothermic, and others to be endothermic? In this simulation, compare the energy absorbed in breaking bonds to the energy released in forming bonds to determine if a reaction will be exothermic or endothermic.

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Investigate the decay of a radioactive substance. The half-life and the number of radioactive atoms can be adjusted, and theoretical or random decay can be observed. Data can be interpreted visually using a dynamic graph, a bar chart, and a table. Determine the half-lives of two sample isotopes as well as samples with randomly generated half-lives.

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Try to estimate the passage of time by selecting a time interval, clicking the Start button, and clicking Stop when you think the interval has passed. The estimate and percent error are recorded. Compare different techniques for estimating time, as well as the average error for long time intervals versus shorter intervals.

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Build compound circuits with series and parallel elements. Calculate voltages, resistance, and current across each component using Ohm's law and the equivalent resistance equation. Check your answers using a voltmeter, ammeter, and ohmmeter. Learn the function of fuses as a safety device.

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Test your hearing range by listening to low-, medium-, and high-frequency sounds. Compare the relative loudness of sounds at each frequency to create an equal-loudness curve. In a quiet room, measure your threshold of audibility for each frequency, and compare your results to others. The volume of each sound can be adjusted.

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Adjust the levels of clothing, perspiration, and exercise to maintain a stable internal temperature as the external temperature changes. Water and blood sugar levels need to be replenished regularly, and fatigue occurs with heavy exercise. Severe hypothermia, heat stroke, or dehydration can result if internal stability is not maintained.

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Observe how a paramecium maintains stable internal conditions in a changing aquatic environment. Water moves into the organism by osmosis, and is pumped out by the contractile vacuole. The concentration of solutes in the water will determine the rate of contractions in the paramecium.

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Observe the effect of predators on a population of parrots with three possible genotypes. The initial percentages and fitness levels of each genotype can be set. Determine how initial fitness levels affect genotype and allele frequencies through several generations. Compare scenarios in which a dominant allele is deleterious, a recessive allele is deleterious, and the heterozygous individual is fittest.

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Determine the angle of refraction for a light beam moving from one medium to another. The angle of incidence and each index of refraction can be varied. Using the tools provided, the angle of refraction can be measured, and the wavelength and frequency of the waves in each substance can be compared as well.

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Observe a chemical reaction with and without a catalyst. Determine the effects of concentration, temperature, surface area, and catalysts on reaction rates. Reactant and product concentrations through time are recorded, and the speed of the simulation can be adjusted by the user.

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Observe evolution in a fictional population of bugs. Set the background to any color, and see natural selection taking place. Inheritance of color occurs according to Mendel's laws and probability. Mutations occur at random, and probability of capture by predators is determined by the insect's camouflage.

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Observe evolution in a fictional population of bugs. Set the background to any color, and see natural selection taking place. Compare the processes of natural and artificial selection. Manipulate the mutation rate, and determine how mutation rate affects adaptation and evolution.

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Observe the wave fronts produced by four closely-spaced emitters. The spacing and phase shift of each wave source can be adjusted, as well as the wave velocity. With all four sources you can observe a region of constructive interference that moves over time. The phased array has several real world applications such as radar and ultrasound.

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Try to click your mouse once every 2 seconds. The time interval between each click is recorded, as well as the error and percent error. Data can be displayed in a table, histogram, or scatter plot. Observe and measure the characteristics of the resulting distribution when large amounts of data are collected.

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Place masses on a circular table and see how fast it spins when struck by a piston. Discover the relationships between angular velocity, mass, radius and moment of inertia for collections of point-masses, rings, disks, and more complex shapes.

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Shine white light or a single-color beam through a prism. Explore how a prism refracts light and investigate the factors that affect the amount of refraction. The index of refraction of the prism, width of the prism, prism angle, light angle, and light wavelength can be adjusted.

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Fire a banana cannon at a monkey in a tree. The monkey drops from the tree at the moment the banana is fired from the cannon. Determine where to aim the cannon so the monkey catches the banana. The position of the cannon, launch angle and initial velocity of the banana can be varied. Students can observe the velocity vectors and the paths of the monkey and banana.

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Explore the laws of motion using a simple fan cart. Use the buttons to select the speed of the fan and the surface, and press Play to begin. You can drag up to three objects onto the fan cart. The speed of the cart is displayed with a speedometer and recorded in a table and a graph.

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Create a graph (bar graph, line graph, pie chart, or scatter plot) based on a given data set. Title the graph, label the axes, and choose a scale. Adjust the graph to fit the data, and then check your accuracy. The Gizmo can also be used to create a data table based on a given graph.

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Launch a charged particle into a chamber. Charged particles can be added into the chamber to influence the path of the moving particle. The launch speed can be changed as well. Try to match a given path by manipulating the fixed particles in the chamber.

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Create circuits using batteries, light bulbs, switches, fuses, and a variety of materials. Examine series and parallel circuits, conductors and insulators, and the effects of battery voltage. Thousands of different circuits can be built with this Gizmo.