There's a good chance you could improve your teaching if you were to:
- relating the action of the lever to conservation of energy
- using separate terms, and separate shorthand, for distances moved and lengths to the pivot
- drawing forces consistently, and as you did during the forces topic
Work through the Physics Narrative to find these lines of thinking worked out and then look in the Teaching Approaches for some examples of activities.
- using a single example, which is liable to misinterpretation
- reducing the topic to a series of algorithmic calculations
- moving too quickly from the physical to the abstract and mathematical
These difficulties are distilled from: the research findings; the practice of well-connected teachers with expertise; issues intrinsic to representing the physics well.
This appears as Ma01TL as Ma01TLnugget10 in the full materials.