What is particularly interesting in the above quote is that energy was seen as being stored not
in one of the two sorts of particles but in their system, "in the middle" as Naomi described it. The
idea that "energy inside needs to be a lot to keep the hydrogen and oxygen apart" as Naomi
explained it elsewhere in the same activity is not trivial, and at the same time is essential for
understanding a large number of biological changes, such as photosynthesis or respiration. Ross
(1993) also argues the importance of reasoning that fuels do not contain energy but rather that the
energy is associated with the fuel-oxygen system, for understanding how the energy is stored.