I can still remember my first microscope. It didn't have a built-in light source so I had to move the little mirror around to capture ambient light and direct it at the object I was "studying". As I recall, the set came with some specimens to look at like a fish scale (I wonder where they sourced fish scales?).
I thought it would be fun to learn a bit about their history and found that the first toy version was manufactured by the A.C. Gilbert Co. in 1934 (see above). Here is how Time Magazine described it in its list of "All-Time 100 Greatest Toys":
Gilbert's scope included a turret allowing three different levels of magnification, which came in handy while peering at insects. (The set included bees, flies and fleas, while instructions encouraged children to collect new subjects on their own.)