I would call some of the sites online and talk to one of the experts that know a lot about microscopes. Yes, you can find good deals on Amazon, but it might not be the best microscope for what your daughter needs for school.
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Microscope off of Amazon: https://www.amazon.com/AmScope-SM-2TZZ-Professional-Trinocular-Magnification/dp/B004U7OYK6/ref=sr_1_10?s=industrial&ie=UTF8&qid=1548724261&sr=1-10&keywords=dissection+microscope
A good stereo microscope should work for dissection and study for planaria.
https://www.microscopeinternational.com/product/accu-scope-3072-stereo-microscope-on-e-led-stand/
You can also find planaria microscope slides online.
Good luck!
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