This model of microscope is what we use:
AmScope M500 40x-1000x Advanced Home School Student Widefield Biological Compound Microscope with Sturdy Metal Framework and All Optical Glass Lenses
I can tell you that this microscope will get your child from elementary through high school. When it arrived, I was immediately reminded of the microscopes we used in high school. And then when we used it, I was impressed.
If you want your child to have a great experience with science studies, I can't recommend this microscope enough.