Microbial Insights has a page especially for kids with seven free, downloadable science experiments on DNA, density, solubility, magnetism, the water cycle, and emulsifiers. Projects such as the Marbled Milk Experiment involve art as much as science.
Each experiment has downloadable, illustrated instructions. The website also has videos for some of the experiments showing how to proceed, but the instructions are very easy to follow on their own.
The experiments are all relatively easy to do--even the DNA extraction! They use mostly household and easy-to-obtain items, although some call for test tubes, a test tube rack, magnets, a graduated pipette, or other scientific equipment.
No special chemicals are required. Even for the DNA extraction experiment, you will use strawberries and make your own extracting solution by combining shampoo or liquid soap, kitchen salt, and water.
Some experiments include more explanation than others, and some refer students to sources for more information. Consider these experiments as supplemental rather than as core curricula.
I expect MI will be adding even more experiments to the page, so check it out now and revisit it later!