Benchmark 8C
The Designed World: Energy Sources and Use
Grades 6-8, page 194

Energy can change from one form to another, although in the process some energy is always converted to heat. Some systems transform energy with less loss of heat than others.

NSES Content Standard B 
Physical Science: Transfer of energy
Grades 5-8, page 155
In most chemical and nuclear reactions, energy is transferred into or out of a system. Heat, light, mechanical motion, or electricity might all be involved in such transfers.

NSES Content Standard B 
Physical Science: Conservation of energy and the increase in disorder
Grades 9-12, page 180
Everything tends to become less organized and less orderly over time. Thus, in all energy transfers, the overall effect is that energy is spread out uniformly. Examples are the transfer of energy from hotter to cooler objects by conduction, radiation, or convection and the warming of our surroundings when we burn fuels.