We are using Elemental Science: Intro to Science. This is by the same curriculum company recommended for the 1st through 12th (?) grades in the WTM book. It gives kids an overview of the sciences and they have a lapbook (optional), experiments that are really accessible for little ones, picture books list, required book being an Usborne Children's Encyclopedia, an activity book for fun activities. Anyway, lots of videos online and a couple by the company themselves too.

Just seeing what happens.