Hello Sherrie,
Kids should have plenty of experience with pocket magnifiers before proceeding to a microscope. Then, the general type of microscope you want is shown here:
https://www.amscope.com/student-microscopes/elementary-k-8/40x-1000x-student-compound-microscope-home-school-science.html
You may wish to go up from here and get a mechanical stage and diaphragm condenser for better control of light, and other features as you may desire. Of course you will need slides, coverglasses, etc.
Please ask further questions as you wish.