• 3-5: 3B/E2. Even a good design may fail. Sometimes steps can be taken ahead of time to reduce the likelihood of failure, but it cannot be entirely eliminated.
• 6-8: 3B/M4a. Systems fail because they have faulty or poorly matched parts, are used in ways that exceed what was intended by the design, or were poorly designed to begin with.
• 6-8: 3B/M4b. The most common ways to prevent failure are pretesting of parts and procedures, overdesign, and redundancy.

• 6-8: 4E/M4. Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves.
• 9-12: 4E/H1. Although the various forms of energy appear very different, each can be measured in a way that makes it possible to keep track of how much of one form is converted into another. Whenever the amount of energy in one place diminishes, the amount in other places or forms increases by the same amount.

• 6-8: 4F/M3a. An unbalanced force acting on an object changes its speed or direction of motion, or both.
• 9-12: 4F/H1. The change in motion (direction or speed) of an object is proportional to the applied force and inversely proportional to the mass.
• 9-12: 4F/H4. Whenever one thing exerts a force on another, an equal amount of force is exerted back on it.
• 9-12: 4F/H7. In most familiar situations, frictional forces complicate the description of motion, although the basic principles still apply.

• 3-5: 4G/E1. The earth's gravity pulls any object on or near the earth toward it without touching it.

• 2.MD.10 Draw a picture graph and a bar graph (with single-unit scale) to represent a data set with up to four categories. Solve simple put-together, take-apart, and compare problems using information presented in a bar graph.
• 3.MD.4 Generate measurement data by measuring lengths using rulers marked with halves and fourths of an inch. Show the data by making a line plot, where the horizontal scale is marked off in appropriate units— whole numbers, halves, or quarters.

An excellent lesson plan developed specifically to go with the PhET simulation Masses & Springs. It's a ready-to-use, inquiry-based activity for introducing frequency and period. Students will be using the tools in the simulation to help them solve a real-world question: Can you design a safe bungee jump? (Link to the simulation can be found in "Activities" below.)

• Physical Sciences K-8 Conservation of Energy and Forces on a Spring Unit