This activity could be part of a bigger theme under pollution. The activity could be the water part and the bigger focus could contain all other types of pollution.

The purpose of this task is to have students add fractions with unlike denominators and divide a unit fraction by a whole number.

The purpose of this task is to engage students in Standard for Mathematical Practice 4, Model with mathematics and as such, the question as it is worded cannot be answered without making some assumptions. For example, if the items that are purchased do not have the same value, then the price reduction depends on the cost of the items.

Spreadsheets Across the Curriculum module/Geology of National Parks course. Students work with salmon-trace streambed data to study whether removal of a spawning run barrier was effective

In this activity, learners explore how different deodorants work. Learners treat agar plates with different types of deodorants and compare the bacteria growth on the plates to the control sample.

This is the first version of a task asking students to find the areas of triangles that have the same base and height, and is the most concrete.

This is the second version of a task asking students to find the areas of triangles that have the same base and height. This presentation is more abstract as students are not using physical models.

The purpose of this task is to provide an opportunity for students to reason about equivalence of equations. The instruction to give reasons that do not depend on solving the equation is intended to focus attention on the transformation of equations as a deductive step.

This real world word problem requires students to figure out the scale ratio and unit rate.

The task provides an opportunity for students to engage in Mathematical Practice Standard 4: Model with mathematics.

The purpose of this task is to give students experience in using simulation to determine if observed results are consistent with a given model (in this case, the Ňjust guessingÓ model). Part (i) also addresses the role of random assignment in the design of an experiment and assesses understanding of this concept.

This task involves two aspects of statistical reasoning: providing a probabilistic model for the situation at hand, and defining a way to collect data to determine whether or not the observed data is reasonably likely to occur under the chosen model. When guessing between two choices, there is no reason to suspect that one outcome is more likely than the other. Thus, a model that assumes the two outcomes to be equally likely (such as flipping a coin) is appropriate.

This task is an example of applying geometric methods to solve design problems and satisfy physical constraints. This task models a satellite orbiting the earth in communication with two control stations located miles apart on earthsŐ surface.

The context of this task is a familiar one: a cold beverage warms once it is taken out of the refrigerator. Rather than giving the explicit function governing this warmth, a graph is presented along with the general form of the function. Students must then interpret the graph in order to understand more specific details regarding the function.

This student activity engages the students' thinking by listening to a story, brainstorming ideas in small groups about how human activity or natural disasters could possibly impact an animal's environment, and then reinforcing that thinking using a board game called Save an Animal.

Students develop an understanding of the concepts of "push" and "pull" as they "save" stuffed animals from danger using LEGO MINDSTORMS(TM) NXT robots. After learning more about the concepts through a robot demonstration, students explore the concepts themselves in the context of saving stuffed animala from the table edges. They choose to either push or pull the animal to safety, depending on the orientation of the robot and toy. They see the consequences of their choices, learning the importance of understanding these force concepts and the differences between them.

In this challenging instructional task students relate addition and subtraction problems to money and to situations and goals related to saving money.

Students gain an understanding of the layers of the Earth by designing and building clay models.

Use a virtual scanning tunneling microscope (STM) to observe electron behavior in an atomic-scale world. Walk through the principles of this technology step-by-step. First learn how the STM works. Then try it yourself! Use a virtual STM to manipulate individual atoms by scanning for, picking up, and moving electrons. Finally, explore the advantages and disadvantages of the two modes of an STM: the constant-height mode and the constant-current mode.