In Stella, students act as astronomers, studying stars in a "patch" of sky in our own galaxy. Using simulated data from spectroscopy and other real-world instrumentation, students learn to determine star positions, radial velocity, proper motion, and ultimately, degree of parallax. As students establish their expertise in each area, they earn "badges" that allow them greater and easier access to the data.

Explore the interactions between a charged balloon and a neutral wall at the atomic-level.

Map the probable locations of electrons around a nucleus to understand probability distributions and the electron cloud model.

How does solar radiation interact with the Earth and its atmosphere to cause global warming? Use this model to see what's going on at the molecular level. Watch the effects of sunlight and then watch the effects of infrared radiation, also known as heat radiation, on the ground and on carbon dioxide, a greenhouse gas.

Students explore two real-life scenarios that involve solving systems of equations. The first situation involves mixing chemicals to create a new solution while the second situation involves cost and revenue for a bake sale. Exploring these situations allows students to see a real-world connection with mathematics. By the end of this lesson, students will have a greater understanding of how using mathematics to model a real-life situation with two variables can help them solve problems.

Students explore two new scenarios that involve solving systems of equations. The first situation involves the travel time for a round trip on an airplane, while the second situation involves calculating the numbers of students and adults attending a high school musical. By the end of this lesson, students will improve their understanding of how using mathematics to model a real-life situation with two variables can help them solve problems.

Manipulate the magnitude of charges on two objects to get a third positively charged particle to hit a target.

Drag the location of charges to get a positively charged particle to the target while observing forces and fields.

Manipulate the location and magnitude of charges to get a positively charged particle to hit a target.

Explore the relationship between the temperature of a gas and the pressure it exerts on its container. This is commonly known as Gay-Lussac's Law or Amontons' Law of Pressure-Temperature. As the temperature of a gas increases, the pressure it exerts on its container will increase.

Explore the relationship between the temperature of a gas and its volume. This is commonly known as Charles's Law. The volume of a gas tends to increase as the temperature increases.

The transition from a solid to a liquid state is called melting. The transition from a liquid to a gas state is called boiling. The temperatures at which particles change state are important properties of substances. Explore why different substances have different melting and boiling points, then create a rule that relates particle attraction to melting and boiling point.

Explore how heat transfers from the outside to the inside of a home through a thermal bridge. The boundary that separates the inside from the outside of a home is called the thermal boundary and includes all sections of the house that are insulated. Garages and attics are often outside the thermal boundary as they are not insulated, unlike the main housing quarters. However, a thermal boundary may also include thermal bridges that enable heat transfer, specifically conduction, between the inside and outside of a home. Conduction is a specific form of heat transfer where heat moves between two objects when they are physically touching.

Explore what happens when a force is exerted on a rubber tire. There are many different types of materials. Each material has a particular molecular structure, which is responsible for the material's mechanical properties. The molecular structure of each material affects how it responds to an applied force at the macroscopic level.

This activity helps students understand translations of functions, where a translation is a movement of the function left, right, up or down. The function retains its basic shape; however, by simply adding to or subtracting from the function, or the x variable within the function, the graph will shift in one of four directions. By the end of the activity students will be able to identify a given function translation, identify the direction the graph will move and graph a sketch of the translated function.

This activity helps students understand dilations of functions, where a dilation is a vertical or horizontal stretch or compression. When a function is multiplied by a number, the shape of the graph will retain its basic shape, though stretch or compress in different directions. By the end of the activity students will be able to identify a given function dilation, identify the way the graph will change and sketch a graph of the dilated function.

A reflection is a transformation of the graph of a function over the x-axis or the y-axis (or both). The function retains its basic shape; however, by including a negative sign in the appropriate place in the equation, the graph of the function will flip over one or the other of the axes. By the end of the activity students will be able to identify a given function reflection, identify the way the graph will change and sketch a graph of the reflected function.

This activity helps students understand all transformations of functions: translations, dilations and reflections. The function retains its basic shape when it is transformed; however, by making small changes to the equation, the graph of the function will be translated, dilated, reflected or a combination of these. By the end of the activity students will be able to identify a function transformation, identify the way the graph will change given a modified equation and sketch a graph of the transformed function.

Transistors are the building blocks of modern electronic devices. Your cell phones, iPods, and computers all depend on them to operate. Thanks to today's microfabrication technology, transistors can be made very tiny and be massively produced. You are probably using billions of them while working with this activity now--as of 2006, a dual-core Intel microprocessor contains 1.7 billion transistors. The field effect transistor is the most common type of transistor. So we will focus on it in this activity.

All cells, organs and tissues of a living organism are built of molecules. Some of them are small, made from only a few atoms. There is, however, a special class of molecules that make up and play critical roles in living cells. These molecules can consist of many thousands to millions of atoms. They are referred to as macromolecules (or large biomolecules).