Benchmark 4E
The Physical Setting: Energy Transformations
Grades 6-8, page 85

Energy cannot be created or destroyed, but only changed from one form into another.

NSES Content Standard B 
Physical Science: Transfer of energy 
Grades 5-8, page 155 
Energy is a property of many substances and is associated with heat, light, electricity, mechanical motion, sound, nuclei, and the nature of a chemical. Energy is transferred in many ways. 

NSES Content Standard B 
Physical Science: Conservation of energy and the increase in disorder 
Grades 9-12, page 180 
The total energy of the universe is constant. Energy can be transferred by collisions in chemical and nuclear reactions, by light waves and other radiations, and in many other ways. However, it can never be destroyed. As these transfers occur, the matter involved becomes steadily less ordered.