*whoooooosh* You have travelled back in time WOW! to Ancient Egypt ooooohh! The towns people (you landed in a town) surround you with weapons and questions.
They demand you show them all the wonders of the future. GOLD and LOvE your reward for something good, PAIN and DEATH if not.

What wonder from the future could you re-invent for them that would blow their MINDS!

N.B You have some tools, including a Phillips screwdriver
Your time.machine is entirely broken so you can't go back....and you didn't build it, so you don't know ship about that

Me - cup and ball game (how do you make string?) and penicilin (that's just mould,right - saw it in quantum leap)