I decided to choose this activity because it looked fun. I tried it with onion and milk.
The onion turned out to be better because when it drys up, you can´t see what I have drawn. But when you cook it, it turns brown without having it burnt and it smells gooooood.
With the milk, you can see the trace where I have drawn on the paper after it drys up. Also it took longer to dry the invisible milk ink and longer to show.
Step it up
Can you find my message what I have written here?