This article provides science content knowledge about forces that shape the Earth's surface: erosion by wind, water, and ice, volcanoes, earthquakes, and plate tectonics and how these forces affect Earth's polar regions.

There is a natural (and complicated!) predator-prey relationship between the fox and rabbit populations, since foxes thrive in the presence of rabbits, and rabbits thrive in the absence of foxes. However, this relationship, as shown in the given table of values, cannot possibly be used to present either population as a function of the other. This task emphasizes the importance of the "every input has exactly one output" clause in the definition of a function, which is violated in the table of values of the two populations.

In this activity, students investigate the simulated use of solid rocket fuel by using an antacid tablet. Students observe the effect that surface area and temperature has on chemical reactions. Also, students compare the reaction time using two different reactants: water and vinegar. Finally, students report their results using a bar graph.

This task can be played as a game where students have to guess the rule and the instructor gives more and more input output pairs. Giving only three input output pairs might not be enough to clarify the rule.

While we know air exists around us all the time, we usually do not notice the air pressure. During this activity, students use Bernoulli's principle to manipulate air pressure so its influence can be seen on the objects around us.

This video highlights students taking scientific measurements to support investigations in atmospheric science, hydrology, soils, and land cover. It shows students reporting data through the Web, creating scientific visualizations for analysis, and collaborating with students and scientists around the world. This is one two introductory videos in the 24-part GLOBE video series. GLOBE (Global Learning and Observation to Benefit the Environment) is a worldwide, hands-on, K-12 school-based science education program.

This video highlights students taking scientific measurements to support investigations in atmospheric science, hydrology, soils, and land cover. It shows students reporting data through the Web, creating scientific visualizations for analysis, and collaborating with students and scientists around the world. This is one of two introductory videos in the 24-part GLOBE video series. GLOBE (Global Learning and Observation to Benefit the Environment) is a worldwide, hands-on, K-12 school-based science education program.

Students design their own logo or picture and use a handheld GPS receiver to map it out. They write out a word or graphic on a field or playground, walk the path, and log GPS data. The results display their "art" on their GPS receiver screen.

Students familiarize themselves — through trial and error — with the basics of GPS receiver operation. They view a receiver's satellite visibility screen as they walk in various directions and monitor their progress on the receiver's map. Students may enter waypoints and use the GPS information to guide them back to specific locations.

Students go on a GPS scavenger hunt. They use GPS receivers to find designated waypoints and report back on what they found. They compute distances between waypoints based on the latitude and longitude, and compare with the distance the receiver finds.

While students need to be able to write sentences describing ratio relationships, they also need to see and use the appropriate symbolic notation for ratios. If this is used as a teaching problem, the teacher could ask for the sentences as shown, and then segue into teaching the notation. It is a good idea to ask students to write it both ways (as shown in the solution) at some point as well.

A gear is a simple machine that is very useful to increase the speed or torque of a wheel. In this activity, students learn about the trade-off between speed and torque when designing gear ratios. The activity setup includes a LEGO(TM) MINDSTORMS(TM) NXT pulley system with two independent gear sets and motors that spin two pulleys. Each pulley has weights attached by string. In a teacher demonstration, the effect of adding increasing amounts of weight to the pulley systems with different gear ratios is observed as the system's ability to lift the weights is tested. Then student teams are challenged to design a gear set that will lift a given load as quickly as possible. They test and refine their designs to find the ideal gear ratio, one that provides enough torque to lift the weight while still achieving the fastest speed possible.

This article provides links to web sites about geologic time, fossils, and the archaeology and culture of the Arctic for elementary teachers.

This task presents students with some creative geometric ways to represent the fraction one half. The goal is both to appeal to students' visual intuition while also providing a hands on activity to decide whether or not two areas are equal.

Students are introduced to gear transmissions and gear ratios using LEGO MINDSTORMS(TM) NXT robots, gears and software. They discover how gears work and how they can be used to adjust a vehicle's power. Specifically, they learn how to build the transmission part of a vehicle by designing gear trains with different gear ratios. Students quickly recognize that some tasks require vehicle speed while others are more suited for vehicle power. They are introduced to torque, which is a twisting force, and to speed the two traits of all rotating engines, including mobile robots using gears, bicycles and automobiles. Once students learn the principles behind gear ratios, they are put to the test in two simple design activities that illustrate the mechanical advantages of gear ratios. The "robot race" is better suited for a quicker robot while the "robot push" calls for a more powerful robot. A worksheet and post-activity quiz verify that students understand the concepts, including the tradeoff between torque and speed.

This article describes how to help students engage with nonfiction text by asking questions, identifying facts, making connections, and reflecting on the text. A template for use with students is included.

The books selected for this list complement articles in the issue of Beyond Weather and the Water Cycle that introduce the concepts of water availability and of extreme weather conditions. In nonfiction and fiction, the books for Grades K-5 emphasize that freshwater is a limited resource and explain how and why extreme weather events occur.