This problem provides an opportunity for children to explore and visualize number patterns and sequences and to reinforce key number concepts and vocabulary such as odd and even, factors and multiples. Students cut consecutive number tracks into equal length pieces in several ways and investigate the patterns that emerge among the sums of the tracks. The Teachers' Notes page explains number tracks and offers suggestions for implementation, discussion questions, a printable sheet of number tracks (pdf), and ideas for extension and support.

In this activity students are asked to relate the numbers 1- 20 to rectangular shapes. Learners use unit squares or cubes to sort numbers by their 'shapes,' either squares, rectangles or sticks (rectangles of unit width). Ideas for implementation, extension and support are included.

This video segment produced for Teachers' Domain features a time-lapse video of clouds forming, changing, and moving across the sky.

This brief video segment produced for Teachers' Domain features time-lapse video of a sunrise and a sunset.

This video segment adapted from Shedding Light on Science illustrates how light changes speed, and thus direction, in a process known as refraction.

This video segment adapted from NOVA follows the clean-up effort after the 1989 Exxon Valdez oil spill off the coast of Alaska. Also featured is a marsh where an oil spill occurred 20 years earlier; analysis suggests that environmental damage may last for decades.

This is an art project where oil paints and water is used. Students will have already explored the densities of oil and water.

This number puzzle helps children develop fluency with pairs of numbers that sum to 10 while applying logic and spatial-visualization skills. Users arrange 9 small triangles within a large one so that the numbers on the matching edges total 10. Students can use the interactive Flash applet or the printable (pdf) triangles provided. The Teachers' Notes page offers suggestions for implementation, discussion questions, ideas for extension and support, and a link to related games (cataloged separately).

In this problem learners explore square numbers and the relationships between them while practicing basic number skills. By applying a systematic strategy they determine three numbers that satisfy the conditions of the scenario. There are links to hints and a solution page; Teachers' Resources include suggestions for implementation, reflection, and differentiation.

Explore an active area of research in optical physics: producing designer pulse shapes to achieve specific purposes, such as breaking apart a molecule. Carefully create the perfect shaped pulse to break apart a molecule by individually manipulating the colors of light that make up a pulse.

A free, open-access organic chemistry textbook (volumes I and II) in which the main focus is on relevance to biology and medicine. This is a PDF version of a wiki project called Chemwiki at the University of California, Davis. There are also supplementary materials, such as PowerPoint slides and a solutions manual available for this textbook at the Chemwiki website.

This video segment adapted from NOVA explains the origin of the elements and how scientists use unique element profiles to identify supernova types.

This video segment adapted from NOVA follows the Apollo 15 astronauts as they collect samples of ancient rock from the Moon's crust, whose discovery helps lead to a radical new theory about the Moon's origin.

In this interactive activity from ChemThink, examine the basic properties of matter at an atomic level and consider how various atoms affect the way a substance behaves.

In 1950, Percy Julian was one of the few African Americans with a Ph.D. He was Chicago's man of the year and a groundbreaking scientist. But it wasn't an easy road. Denied teaching positions and the target of death threats, Julian struggled to get ahead in a racially hostile world. Learn more about Percy Julian's contributions to science and civil rights. These resources, adapted from NOVA: Forgotten Genius, explore how Julian revolutionized chemistry with the first synthesis of a chemical compound, as well as the challenges he overcame as an African American facing legalized segregation.

This interactive periodic table developed for Teachers' Domain provides detailed information about the chemical properties of elements and illustrates the electron configurations that determine those characteristics.

See how light knocks electrons off a metal target, and recreate the experiment that spawned the field of quantum mechanics.

See how light knocks electrons off a metal target, and recreate the experiment that spawned the field of quantum mechanics.

Watch the rubber bands vibrate on homemade guitars in this video segment adapted from ZOOM as cast members talk about pitch and demonstrate how to make a cereal box instrument.

This video segment, adapted from ZOOM, explores the different sounds that a simple drinking straw can produce when you cut the straw and blow into it.