Spaghetti / marshmallows always works.

Plus has the added bonus that you get to leave the teacher with a classful of kids ripped off their gourds on sugar and E-numbers.

Cocktail sticks and wine gums… easier to build stuff than the spag and marshmallows.

You could use a bike on a stand to demonstrate levers by going through the gears. Would start with weights on a seesaw though.

If you could have something unliftable for the kids that becomes liftable by moving the fulcrum.

As a retired DT teacher a practical lesson on simple levers works really well with a simple beam & fulcrum. Get a stout piece of timber 2″x2″ sq+ and about a metre+ long. Organise the children around a table and arrange a test with the strongest (they always volunteer a champion) and another – possibly the smallest. Adjust the fulcrum to give the underdog + + mechanical advantage serupticiously.

This is a real eureka moment (no pun intended) when the underdog is proved to be stronger than the strongest. Various others will want to try it & you can furtively re-position the fulcrum each time. They are slow to get it – but eventually someone susses it out. Some smaller sets of simple equipment could be supplied so they could try it in small groups.

This can be followed up by llooking at a range of level types in real objects (pliers / scissors / nail clippers / garden shears / bolt croppers / tweezers / wheel barrow? etc) to identify the the position of the fulcrum / pivot & the likely MA.

I have used worksheets to reinforce learning with this principle – but they could be asked to draw pictures to record what they have learned.

Good luck with this – it generally works very successfully.

For the forces part there’s fun to be had with gyroscopes. A bike wheel and spinny chair combine well.

Maybe combine some electrolysis and the bottle rocket.

what did you do?

Unbelievably, it was cancelled the week before.
Gutted and relived in equal measures.

Why not just get them to create a BIM model, all the rage these days.