Here four steps in developing an energy description map to three levels of description.
The structure of the energy descriptions, which is part of a passage of teaching consists of three levels:
Level one is located in the lived-in world and consists of a description of changes in everyday objects using common terms.
Level two has two complementary halves. The first half is an operationalisation of measures by a process of noticing and recording elements of the lived-in world, bring them into focus so that they can be a part of a physical description. The second half is complementary to this and provides imagined mechanisms which can be a mental model to enable you to get a grip on what is happening during a process( and so provide an explanatory mechanism).
Level three is where the idea of energy gets a grip: it depends on the operationalised measures established in the second level. Still, it does not depend on (a grasp of) – and, complements – the physical mechanisms described in the second level.
Best not to try and jump straight to questions about energy changes: it does not end well.
Any proposed passage of teaching, which invokes the idea of energy should develop this idea through the levels. Developing an energy description involves working through the levels: to avoid pain don't jump straight to an account in terms of energy. This structure should reduce difficulties by providing a framework in which talk about energy is much more likely to consist of sensible talk, and not a word game.
Try using non-verbal resources to complement the words, as words by themselves are somewhat slippery, and not well suited to introducing children to precise yet abstract ideas.