After our normal school work this morning, we tried the "invisible ink" experiment. We used lemon juice to write on paper, let it dry, then tried to see it. No avail. Holding the paper to a strong light didn't work so I read on the omniscient internet that using an iron (without steam) would heat the paper enough to divulge the message. Still no go.
He was disappointed.
from Mom & Kiddo. Moon craters using flour.
This kept him occupied for quite a while and of course turned into free play.