Science Assessment

Students should know that:

1. The elastic potential energy of an object is related to both the amount the object is stretched, compressed, twisted, or bent and how difficult it is to stretch, compress, twist, or bend the object. The amount of elastic potential energy an object has can be determined from these two factors alone, and not its mass.
2. Any elastic object that is stretched, compressed, twisted, or bent has elastic potential energy. An elastic object that is not stretched or compressed has no elastic potential energy. 
3. For elastic objects that are identical except for how much they are stretched or compressed, the object stretched or compressed the most will have the most elastic potential energy and the object stretched or compressed the least will have the least elastic potential energy.
4. For elastic objects stretched or compressed the same amount (greater than zero), the object that was the most difficult to stretch or compress has the most elastic potential energy, and the object that was the least difficult to stretch or compress has the least elastic potential energy. 

Boundaries:

1. Assessment items do not ask students to use formulas, such as ½kx², to calculate elastic potential energy. The sub-ideas above describe semi-quantitative relationships. Students are expected to compare relative amounts of deformation (stretch, compress, twist, or bend) and how difficult it is to deform the objects to determine relative amounts of elastic potential energy.
2. Students are not expected to know which objects are more or less elastic than others.  Assessment items use only familiar elastic objects such as springs, rubber bands, and rubber balls.  Students are not expected to know the stiffness or rigidity of specific materials or the spring constants of specific springs.  In assessment items, the relative rigidity is provided when necessary.
3. Items may involve objects stretched, compressed, twisted, or bent.  In items, comparisons are made between objects stretched, compressed, twisted, or bent in the same manner (i.e., both bent). Items do not use situations where one object is stretched and another object is compressed.  Additionally, items do not compare an object in a stretched and compressed state.
4. In assessment items, objects are not stretched, compressed, twisted, or bent beyond the point where they would return to their original shape (i.e. no plastic deformation).
5. When dealing with springs, students are not expected to know the effect of combining springs in series or parallel on the elastic potential energy of the springs.  Students are also not expected to know about how the geometry of the spring relates to the overall elasticity of the spring.