Science Assessment

Students should know that:

1. Even though the forms of energy present within a system may change, the total amount of energy in the system remains the same unless energy is added to or released from the system.
2. If the total amount of energy in a system decreases or increases, an equal amount of energy must have gone to or come from somewhere outside the system.
3. If no energy enters or leaves a system, a decrease of one form of energy by a certain amount within the system must be balanced by an increase of another form of energy by that same amount within the system (or a net increase of multiple forms of energy by that same amount).  Similarly, an increase of one form of energy by a certain amount within a system must be balanced by a decrease of another form of energy by that same amount within the system (or a net decrease of multiple forms of energy by that same amount).
4. Energy can neither be created nor destroyed but it can be transferred and/or transformed within and between systems.
5. If energy is transferred to or from a very large system (or a very complex system), increases or decreases of energy may be difficult to detect and, therefore, it may appear that energy was not conserved.

Boundaries:

1. Assessment items avoid using the phrase “energy conservation” or “conservation of energy” because students often associate these terms with efforts to conserve energy resources.
2. Assessment items do not ask students to make calculations about the amount of energy in a system or about changes in energy.
3. Students are not expected to know about energy-mass conversions such as nuclear reactions or other subatomic interactions.

Students should know that:

1. Unless prevented from doing so, energy will become uniformly distributed among the atoms/molecules within a system or between the system and the surrounding environment.
2. When energy becomes uniformly distributed, the amount of energy present has not changed but the energy becomes less useful and less concentrated.
3. After a given amount of energy had become uniformly distributed, it takes additional energy to concentrate the diffuse energy and make it useful again.
4. Thermal energy in the surrounding environment is sometimes considered a less useful type of energy.

Boundaries:

1. Items do not ask students to perform any calculations. For example, students are not asked to use equations like KE = 1/2mv² or PE = mgh.
2. Items do not assess students’ understanding of entropy or the relationship between energy and entropy.