My toddler loves Curious George. He loves reading the Curious George books over and over again. One of our favorite set of Curious George Books are the 
Discovers series. We reread these several times a day. Curious George discovers and learns something about science ranging from the Sun, Stars, Space, Rainbow, Germs and the Senses. Each Discovers book shares what George learns, has science facts, and activities to go along with the book. I love reading these books to my toddler and then doing the activities to help reiterate what we've learned. 
In Curious George Discovers the Sun, George learns about solar power and heat from the sun. The activity that goes along with the book includes instructions on how to make your own solar oven using items commonly found in a home. My toddler and I enjoyed construction our solar oven and baking smores in it. I would highly recommend these books to all preschoolers. The Curious George Discovers Series can be found at your local library or here
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