Secondary science teachers - do you have a fail-safe fun lesson?

[anchovies]

I have just finished my PGCE and am going back to my placement school tomorrow to teach a year 7 class a one off lesson. I have promised them something fun!

Was thinking of doing an egg drop challenge but was wondering if anyone has any fantastic fun lessons that they could share?

TIA!

Bit late now, but my Y6 really enjoyed building a structure out of marshmallows and spaghetti.

Making slime. Discussing how it acts as a liquid and a solid. And how it looks like bogey if use green food colouring. My local hardware store always get me the borax.

Flame tests!