User Yoshinok over at Instructables published a step-by-step guide to converting any smartphone into a portable digital high powered microscope. The hack utilizes a cheap laser pointer lens, but if you want to have better quality optics, an old DVD player lens is also good. The guide can be used for any smart phone, as long as you modify a stand to accommodate your phone’s dimensions.
This is not only a great project to do with your kids, but can also be used to create a quality microscope for practical use.
More at Instructables: $10 Smartphone to digital microscope conversion