How to Make the Simplest Microscope for Water

I've always been wondering what things like bacteria really look like up close. However, professional microscopes nowadays cost upwards of $10000! A while ago, I saw a tutorial on how to see tiny little organisms inside of water using a laser pointer and decided to try it out but modify it a little bit.

1. Laser Pointer - This is the supply that many people may not have however, any type of laser will work. It doesn't have to be a dedicated laser, it could be something like a laser distance measurer or a presentation laser pointer.
2. Empty Container of Fruits - It doesn't specifically have to a container of fruits, but anything like a plastic film that doesn't bend much and is pretty straight.
3. Muddy or Dirty Water - If it doesn't rain much in your area, don't worry! You can copy me and do what I did.
4. Scissors - If you are a young kid, please take help or at least supervision from an adult or parent.
5. Syringe - If you don't have a syringe like me, I will show you how you can use a straw instead to pick up water.
6. (Not Pictured) Hole Puncher - Make sure your hole puncher doesn't break easily and if possible, get a single-hole puncher. This is because we will need to make a hole in the plastic which can be pretty tough. I do not recommend using scissors for 2 reasons: 1. The hole needs to be pretty small and perfectly round which is hard to do. 2. Trying to cut the small hole with scissors on a sharp piece of plastic is just not a good idea for safety reasons so please do not try it.
7. (Optional) Chocolate - Just a small treat to reward yourself for trying a new STEM challenge!

The main reason why we need to use a laser and not a flashlight is because lasers emit light in a single focused ray. This means that when we shine it through the water, it will have less of a tendency to spread out everywhere (Image 1). Also, lasers give out light in a single consistent frequency. Flashlights however have multiple frequencies so we will get different refraction patterns when we shine it off something (Image 2). (Pls ignore the typo; these are not my images)

If you don't have a syringe like me, I recommend using a straw. When you insert the straw into a liquid, it should fill up until the height of the liquid. In order to stop the water from falling out, you simply have to cover the top of the straw with your finger. The reason why this works is because when you cover the top, you are essentially blocking out air to go in from the top of the straw. So now, the water can't fall out through the bottom, because there will be no air that can go in and replace it. This may sound complicated, but once you understand it, it'll seem super simple. In the third image, note how the water doesn't fall out of the straw but just stays suspended in the air.

If it's rained recently near your house, pick up some of the water off the ground either using a syringe or the straw method. If you don't have a muddy puddle, what I did was grab some dirt/soil and tap water in a disposable cup. Please do not use a reusable cup. This is very unsanitary and who knows what types of bacteria you will be drinking out of it next. For my example, I used an empty Yakult bottle.

If you used the the dirt and water method, make sure to mix thoroughly. The dirtier our water is, the better of an example it will be because you will see more microbes and bacteria. Make sure the water isn't clumpy; there should still be a part that is completely liquid which we will use as a sample. Again, please do not use any non reusable utensils. I just used my disposable straw to mix it and suggest you do the same.

Now, we're going to cut out a little part of the plastic that will hold the water. Carefully, using the scissors (with adult supervision), cut out the lid of the box. Then, cut out a square or similar shape from the flat part of it. Remember to use caution when cutting as the plastic is tougher than most papers. Yours does not have to be as big as I made it in the second photo; in fact, I ended up cutting it even smaller. I recommend you don't make it too large as it will be hard to hole punch it.

In this step, we will hole punch the plastic. If you don't have a hole puncher, I really recommend not trying to use scissors as it will be very hard to and you will end up hurting yourself in the process. Try to make the hole in the middle but it doesn't really matter. For me, my hole puncher took a lot of strength to punch a hole since plastic is a lot tougher than what it was meant to handle. If you cannot do it, don't try to force it, just take help from an adult.

Now, we'll try to place water into the hole we just created in the plastic. This will serve as our bacteria model. Take some of the dirty water from the cup using the straw and try to let it go into the hole. Make sure to hold the plastic in the air when you do this otherwise it may not work. I just have it on the table in the image because I was also holding the camera in one hand. If necessary, use a small napkin to absorb any of the water on the plastic that is not in the hole. The water in the hole should look like the third image.

The exact science for surface tension is a little complicated so I'll put it in a much easier way for you to visualize; water loves to stick to things. It's just like how water beads can stay on a cold bottle of water without falling off. In our example, the water was sticking to the edges of the hole we created which was why it stayed there. Because our hole was a perfect circle, there was equal force from all sides of the center of the water which caused it to stay better balanced. This may sound confusing to you, but I'll make a separate mini experiment for you. Take water on any object that it will stick to, like a water bottle. Move another object and make it barely touch the water, and you'll see how the water will shift and attract to the second object as well.

The final step, what you all have been waiting for. First, you'll need to move to a dark room with a blank wall. Next, hold up the plastic card with the water parallel to the wall. Lastly, turn on the laser and watch the magic happen. Make sure the laser is pointed directly into the water hole for the best results.

The reason why we can see the shadows of the bacteria is kind of like a projector. In a classroom, you may have noticed when someone walks by the projector, you can see their shadow in the projector because they are blocking the light from reaching the screen (or wall in this scenario). But how come when someone walks past the projector, you can't see the bacteria on them? Well, that's where the water comes in. The water doesn't just serve as the bacteria holder. We used water because of its ability to bend light. When the light bends, it acts like a magnifying glass which is the reason we were able to see so close up.

Come on, you gotta reward yourself with something. For me, it's always sweets ;). This was also conveniently posted the day after Halloween so you guys should have plenty of candy already!

This is my first ever Instructable and I've entered it into the Visualize It competition. If I am able to win, I will be very happy, so try to boost my model by trying it out, liking it, and sharing it with others. Also a huge thanks to Autodesk for hosting this amazing platform. I was introduced to this from one of my teachers at school and I'm so surprised I've never seen this before.