Sal shows that a commutator can be used in order to keep the loop of wire rotating in the magnetic field. Created by Sal Khan.

Sal finishes the explanation of how a commutator will allow a loop of wire to continue spinning in a magnetic field, thereby allowing it to work as an electric motor. Created by Sal Khan.

In this video David explains how to find the electric potential energy for a system of charges and solves an example problem to find the speed of moving charges. To see the calculus derivation of the formula watch this video. Created by David SantoPietro.

In this video David shows how to find the total electric potential at a point in space due to multiple charges. Created by David SantoPietro.

In this animation produced by WGBH and Digizyme, Inc., see how molecules of DNA are separated using gel electrophoresis, and how this process enables scientists to compare the molecular variations of two or more DNA samples.

In this electrochemistry activity, learners will explore two examples of electroplating. In Part 1, zinc from a galvanized nail (an iron nail which has been coated with zinc by dipping it in molten zinc) will be plated onto a copper penny. In Part 2, copper from a penny will be plated onto a nickel.

In this activity, learners conduct a simple experiment to see how electrically charged things like plastic attract electrically neutral things like water. The plastic will attract the surface of the water into a visible bump.

A learning activity for the "Do You Know That Clouds Have Names?" book in the Elementary GLOBE series. Each student will be given the opportunity to create their own cumulus cloud out of white paper and mount it on blue paper. Students will also complete the Cloud Fun Student Activity Sheet that includes a description of the cloud and what the weather was like on the day the cloud was observed. The purpose of the activity is to help students identify cumulus clouds and observe the weather conditions on days that they see cumulus clouds. Students will learn about a cumulus cloud's shape and appearance, how to verbally describe cumulus clouds, and what the weather is generally like when these clouds appear in the sky.

A learning activity for the "Do You Know That Clouds Have Names?" book in the Elementary GLOBE series. Using information from the book and their observations, students construct a sky scene with trees and buildings as reference points on the ground and cloud types ordered by altitude in the sky. Students will describe clouds using their own vocabulary and will then correlate their descriptions with the standard classifications of cloud types used by the GLOBE Program. The purpose of the activity is to help students identify some of the characteristics of clouds and to enable students to observe clouds, describe them in a common vocabulary, and compare their descriptions with the official cloud names. Students will be able to identify cloud types using standard cloud classification names. They will know that the names used for the clouds are based on three factors: their shapes, the altitude at which they occur, and whether they are producing precipitation.

A learning activity for the "Do You Know That Clouds Have Names?" book in the Elementary GLOBE series. Using information from the book and their observations, students construct a sky scene with trees and buildings as reference points on the ground and cloud types ordered by altitude in the sky. Students will describe clouds using their own vocabulary and will then correlate their descriptions with the standard classifications of cloud types used by the GLOBE Program. The purpose of the activity is to help students identify some of the characteristics of clouds and to enable students to observe clouds, describe them in a common vocabulary, and compare their descriptions with the official cloud names. Students will be able to identify cloud types using standard cloud classification names. They will know that the names used for the clouds are based on three factors: their shapes, the altitude at which they occur, and whether they are producing precipitation.

The class will brainstorm, write, create, and produce a play in which they represent how all the Earth systems are interconnected. This play can be based on the Elementary GLOBE book "All About Earth: Our World on Stage" or on other student-generated topics representing interconnections of the Earth systems. The purpose of the play is to serve as a performance assessment providing students with the opportunity to display what they have learned about the Earth as a system in a creative manner. Through this activity, students will demonstrate their knowledge of how the hydrosphere, atmosphere, geosphere and biosphere interact.

A learning activity for the "All About Earth: Our World on Stage" book in the Elementary GLOBE series. In pairs, students will create experimental conditions in terrariums in order to study what plants need to live. Variables to study include the presence or absence of soil, water, and sunlight. Students will record the growth of radish plants as well as observations of "the water cycle" in their terrariums. At the conclusion of their experiments, students will share their results with the class and discuss how water, Earth materials, and air are all necessary to support living things. The purpose of the activity is to acquaint students with the hydrosphere, geosphere, atmosphere, and biosphere more closely, to have students use microcosms to study natural phenomena, and to introduce students to the concept of a "fair test" in a scientific investigation. After completing this activity, students will know about the importance of the hydrosphere, geosphere, and atmosphere in supporting the biosphere. They will learn how to set up "fair test", record detailed observations, use drawings as scientific records, make sense of experimental results, and share them publicly.

A learning activity for the Scoop on Soils book in the Elementary GLOBE Series. Each student will make predictions about the properties of various soil samples. Then they will examine several types of soils and record their observations. Next, they will learn about soil profiles and horizons by both examining a soil sample in a jar and by creating a soil profile flip chart. The purpose of the activity is to provide the opportunity for students to ask questions and make observations about soil and introduce students to the properties of soil and to the concept of soil profiles and horizons. After completing this activity, students will know about soil's different properties and about soil profiles. Students will know that soils have different properties including texture, color, and size. They will know that soil forms layers based on these properties.

Students will learn about magnification and how a magnifying lens works. They will examine a variety of different objects, first without a magnifier and then with a magnifier, and compare what they observe. They will practice observing details of these objects with magnifying lens. The purpose of this activity is for students to learn about observation skills and how tools can help people make observations, what "magnification" means, and to learn that scientists use tools, such as magnifying lenses, to examine objects. Students will be able to identify a magnifying glass and its purposes. They will be able to describe how the same object looks different when using the unaided eye versus a magnifying lens.

A learning activity for the Scoop on Soils book in the Elementary GLOBE Series. Students will make predictions about what they think they will find in a sample of soil. They will investigate the sample and sort out the various items they find. Next they will spend time outside observing one or more sites to see what they find in the soil. After recording and sharing their observations they will create their own stories about the things they found in the soil. The purpose of the activity is to learn about natural things commonly found in soil and how these things impact how the soil looks and feels as well as to introduce students to the concept of decomposition. After completing this activity, students will know about various things found in soil including rocks, critters, roots, and other organic material. They will also understand that animals and microorganisms aid in the decomposition process that contributes organic materials to soils.

A learning activity for the "Do You Know That Clouds Have Names?" book in the Elementary GLOBE series. Students will explore the difference between the three types of contrails, make observations of contrails outside, and record their observations. Fifteen minutes later they will make follow-up observations to see how the contrails they observed have changed. The purpose of the activity is to help students identify contrails and learn to distinguish between the three types of contrails and to understand that contrails are human-made and some contrails become clouds in the sky. Students will be able to (1) identify the three types of contrails; (2) understand that contrails are created by jet airplanes; and (3) understand that some contrails become clouds.

Learn about the fundamental connections between math and music, in four Acts: Rhythm, Frequency, Harmony and Fractals. Concepts presented in the video documentary are reinforced by hands-on experiments using the Google Chrome Music Lab Experiments.

Most orbiting bodies follow a path that is an ellipse. In this activity, students construct 2 ellipses, and examine and measure them to determine some of their fundamental properties. The exercise helps learners make comparisons to planetary orbit eccentricities, and includes guidelines for constructing a scale model of Haley's comet.