Science is important for understanding how the physical things in the universe work. The more we understand science, the better we will be able to use the things we have. It is also important to note that younger children learn most things quicker than we think, look how fast they pick up words and expressions as well as learn language and reading and compare that to an adult learning a foreign language. Thus it stands to reason that we should start children on science as early as possible, and that means elementary school! Chemistry is an important science that young children can be taught the basics.
Teaching chemistry in elementary school is different from the older grades. Young students learn best form doing and will get the principles as they go along. So experiments are best. Now rises the question of what chemistry experiment are best for demonstrating sound principles, but still safe for young children? It needs to be something basic, but fun if the children are to really learn well!
Simple chemistry experiments can include the "volcano mixture" of mixing vinegar with baking soda and doing it around a candle to show the production of carbon dioxide. You can also boil sugar in water and make it supersaturated, the add a grain of sugar and show crystal formation. This will almost look like the magic Ms. Frizzle does in the Magic School Bus Series. You can actually use ideas from the series!
One good book that does this, and is also available as a video is The Magic School Bus gets Baked in a Cake. A book about kitchen chemistry. There really is something called kitchen chemistry! This is using compounds found in the kitchen to mix and match things to teach chemical principles. It is fun, exciting and has some very valid chemistry experiments suitable for young children! You can show the video, then do the experiments in the class!
If the class is a bit more advanced and responsible, you should get the Horrible Science Series, with Chemical Chaos. by Nick Arnold. It is about how chemistry can go wrong, but comes with numerous safe chemistry experiments that most classes will enjoy, and can do without breaking the budget!
Chemistry, it is fun and exciting and should be started in elementary school. These books will definitely help with finding suitable experiments!