Very cool! I also had such a children's microscope, it was my favorite "toy" for quite a while. Later, in my biology classes with the "better" microscopes, there were hardly any more interesting hours than the exploration time.
Have you already magnified hair? There are visible differences in the structure (not only the color) of blond and dark hair. Sheep hair compared to dog hair is also interesting. Insects are the most fascinating. You might find a dead spider or fly. Or you - sorry, guys, it's for science - crush a mosquito....