All the physics and metallurgy things. I am also slowly acquiring skills in construction and farming.

Don't forget beer making! I understand enough about distillation to probably make liquor without killing people.

Building basic flying machines.

Don’t. Civilization kinda fucked the planet and is the reason you live in a post-apocalyptic wasteland.

The sign of a ball with three rays shall be repulsive for thee, thou shalt not enter any shelter nor edifice with the sign of a ball with three rays, nor destroy spoken buildings.

And to react to @bool@lemm.ee I would probably be able to write some primitive method of computing the logarithms.

Does it count if I have been keeping a copy of all the Kiwix releases and could submit those documents? It would certainly be one hell of a kickstart.

Otherwise, screw civilization... Here's how you build and tune a trebuchet (yeah I have a bit of experience with the construction, as long as someone else supplies the rope).

Never trust someone who says one thing but tries to do another, or who's inconsistent on something while saying they're not.

Can't go wrong with the Old Testament, amirite guise?

Some basic concepts of medication - clean wounds (preferably with alcohol, because it kills germs), understand how germs spread, and know the basic ideas behind vaccines. If society had known these things 1000 years ago, it would've saved billions of lives.

As many works and studies about morality and ethics as possible, because god knows we threw those out the window long ago, and it's biting our asses now. I'd also add an emphasis on John Rawls' works, particularly "Justice as Fairness: Political not Metaphysical" and "A Theory of Justice".

I'm not sure there is anything I could contribute that someone else couldn't. Probably basic germ theory?

My contribution is a very practical tip for parents: When you need to carry a kid sitting on your shoulders, first pick them up and have them sit with both legs on your right shoulder. Then, with your right hand, grab the kid's right leg, and with your left hand grab the kid's left leg and lift it over your head to place it in your left shoulder. Mirror the maneuver if necessary. The result is a quick lift-sit-and-switch technique, and fewers kicks to the head.

How to make fire

How to get rid of hiccoughs. No one knows this trick! All you need to do is hold the flaps of your ears closed and drink a little water. It works every time!