Children are very curious so they like asking questions that my husband and I don't know the answer to. Enter: Google. Now we all know what causes thunder. The internet is an amazing repository of educational material. To me, it is books in digitized format, and then some.
Through YouTube, my kids have also watched ballet and folk dances, how a chick hatches from an egg, and how to bake and decorate a variety of cakes. Yes, they love egg surprise and toy unboxing videos too - I make sure they watch the narrated ones.