After attending a STEM session at the 2016 NAEYC Conference, I was inspired to buy a USB microscope.
I purchased the Plugable USB 2.0 Digital Microscope
I hooked it up to my MacBook but I use a different matte monitor so it cuts down on the glare from the mac screen. The little arm is great for setting things at a fixed focus for the kids to put leaves or bugs or whatever they want to look at. The software even lets you take pictures! Which is SUPER useful. Overall it is pretty easy to use.
I just have to remember to store it inside!