Your smartphone is good for a lot of things, but I'm willing to bet you mostly use it for taking selfies, texting, checking email, and playing whatever new, crappy mobile game takes the edge off your bleary-eyed commute to work in the morning.
But if you feel like getting more value out of your device, may I suggest this very easy guide by Gross Science for turning your smartphone into a working microscope.You'll need: a smartphone (duh), any cheap laser pointer, poster tack, a flashlight, white paper, stiff clear plastic, and something preferably dirty (in this case, pond water) to look at.
How to enhance your phone
Grab your laser pointer because you're going to remove the lens from it. You can do this by taking the top off and jabbing something skinny into it until the lens comes out.
Take a little piece of poster tack, roll it into a thin strip, and wrap it around the edges of the laser pointer lens you just removed.
Stick the lens (the rounded side should be facing outward) over your smartphone's camera. Make sure it's securely adhered. According to Tested, all laser pointers are equipped with a small lens that "focuses the light that comes out of the laser diode." Coincidentally, they add, it also happens to be the perfect size for iPhone camera lenses, and allows you look at things with a short focal length—perfect for viewing microscopic subjects at a greater magnification.
Good job. You followed directions and now you have a cool, portable microscope.
How to look at stuff
You'll need to prepare your sample first (the pond water, remember?). To do this, cut out a 3" x 3" square of white paper, and place it on top of your flashlight. Cut a similarly sized piece of clear plastic and place that on top of the white paper.
Take a drop of your pond water and place it on top of the clear plastic. Cut out another, smaller piece of plastic and gently set it on top of your sample, so that it's sandwiched between the layers like two microscope slides.
Place your smartphone on something that's higher than the flashlight and center the lens over your slide. Put your phone on video mode and zoom in so you're focused on your sample. Look at that! Check out those microorganisms or whatever other gross thing you're looking at up-close.
Take lots of videos and upload them to Facebook or whip them out at parties to impress your friends.