Thin film interference occurs when light waves reflecting off the top and bottom surfaces of a thin film interfere with one another. This type of interference is the reason that thin films, such as oil or soap bubbles, form colorful patterns. Created by David SantoPietro.

Let's work out a few details on how thin film interference works. Created by David SantoPietro.

This interactive activity from the NOVA Web site challenges you to think like Einstein and understand how time travel might be possible.

In this activity, learners overlap the three primary colors to see how all other colors are made. This activity also explains how color can be explained by the subtraction of colors of light, related to the principles of absorption and reflection of light.

This video from NASA explains the process by which gamma-ray flashes associated with storms produce matter/antimatter particle pairs.

This illustrated essay from the NOVA Web site answers questions about irregularities in the tides.

In this exercise, students use online data, spreadsheets, and graphs to analyze tidal fluctuations at the Battery in New York. They will be asked to examine and compare the observed and predicted tides, and then make their own predictions.

In this activity, students play the roles of time travelers and travel to the Archaean era to learn what early Earth was like during that time. They collect information on the Archaean atmosphere, life forms, and landscape, and write a report that summarizes its characteristics. A scoring rubric for the report is provided.

In this activity, students create two- and three-dimensional maps by using a data grid of an imaginary section of Earth's surface. They are challenged to create six different maps of various surface features and answer questions about them.

In this video segment adapted from NASA, learn how engineers are transforming the future of flight by designing airplanes based on principles found in nature. In the early 1900s, the Wright Brothers found inspiration for their first airplane in nature. Their "Flyer," which was modeled on a bird's flexible wing design, was steered and stabilized by pulleys and cables that twisted the wingtips. Despite its success, this control strategy quickly vanished from aviation. Instead, stiff wings capable of withstanding the greater forces associated with increased aircraft weights and flying speeds became the standard. In this video segment adapted from NASA, learn how designs found in nature have inspired today's aerospace engineers as they conceive the next-generation of flying machines. Grades 3-12.

In this activity, students play the roles of consultants in developing a geologic 'tour' south od Rochester, New York, near the Pennsylvania border. They will gather information on the local rock types and underlying geology, examine an assemblage of fossils from the bedrock and from glacial erratics, and prepare a report detailing the geology with cross-sections and a timeline based on the fossil occurrences. They will also develop a plan for a walking tour highlighting the geology of the area.

Watch the ZOOM cast build a chair out of newspaper by making good use of the strength of triangles.

In this video segment adapted from ZOOM, the cast tries to design and build a bridge made out of drinking straws that will support the weight of 200 pennies.

This interactive activity, from the Building Big Web site, explores tunneling and the tools and methods used to do the job.

This video segment presents a variety of sounds -- from animals to machines to musical instruments -- while introducing the basic concepts of vibration, volume, and pitch.

Four unit plans provide opportunities for in-depth explorations of important foundational climate concepts -- weather, water as a solid, liquid and gas, and the water cycle -- that are appropriate for K-2 and 3-5 learners. These unit plans incorporate many of the lessons highlighted in other articles in this issue of the online magazine Beyond Weather and the Water Cycle. The magazine is structured around the essential principles of the climate sciences.