The Germ Detector

I will be doing an experiment using a UV light and a plastic square. I am trying to see what object has most germs. The plastic square is used to calculate the percentage of germs. Then I turned my percentage in to a graph.
Abhijot Rai
Grade 6


Dirty sponges have most bacteria on them because other objects can get cleaned but we use sponges to wash dirty dishes so instead of the sponges getting cleaned they get dirtier. Also sponges cannot thoroughly get cleaned because after we wash them we are going to repeat the whole process again, this is why we should change our sponges frequently. Another reason is when people use forks and spoons their saliva gets on the dishes, then we use the dirty sponges to clean and all the saliva is on the sponge. When we use the sponge again all the saliva gets on other dishes.  



Touch screens such as fast food order machines, atms, arcade machines, self cash machines and gas pumps include many germs because employees may clean common places like floors. But the locations that individuals touch most are not sanitized because it is very time consuming, for an example going to each arcade machine everyday can take very long.


It is very disgusting to know that everytime you flush a toilet all the unsanitary water droplets reach up to the hand dryers. Eventually someone uses the handryer and the pressure of the air blows all the bacteria to the person's hands. You probably never knew that after you washed your hands and used a hand dryer you gained all the germs back. 


Most adults probably tell you to hold a railing while you walk up the stairs to be safe but is it really safe? It might be safe in a way but if you thought this the sanitary way it is 100 times worse than a toilet. In many schools people clean railings but still  everyday more than 50 kids touch them with their hands.  Now because of covid school hand rails get clean all throughout the day but before this pandemic we did not have very clean handrails.


When we think of soap dispensers you never think about getting germs from there because we use the soap to clean our hands but if the soap is on the inside what is on the outside. Before a person washes their hands they touch the stall doors, stall locks, toilet paper and their germy pants. Then they get to the soap dispenser to get some soap, while they smear their hands all over the soap dispenser. I guess they wash their hands after but from the sink to the door out they could touch so much. For example doors, closing the tap and kids dragging their hands across walls. 


Grocery shopping is one of the places we wish to get clean foods, toiletries, objects and other necessities, but even if they were clean we make them unsanitary. When we use shopping carts we constantly touch objects in the stores and then we grab our shopping carts, doing it again and again. How do we know that the groceries were not touched by people? Also us humans have temptations of touching at unnecessary times so who knows what the person that had the cart before you has touched?


Whenever we have a special celebration we eat cake, specifically on birthdays we light candles and make a wish. Long story short it was cousins birthday and she said “Eww I don't want to put candles on my birthday cake!” I was super confused but now I finally understand why she said that. When we blow candles all the little germy tentacles fly on to your cake. How many people eat that cake? All your saliva or germs end up in someone's mouth. Never will I ever put candles on my cake again!


Many people say that money is happiness but is it really happiness? How many people have owned your money before you? Money is something that never ends. The money you have has probably been touched by more than a thousand people. After touching money you touch more then 10 things at least. Even if you think you're so clean you may be the reason that germs are spreading, in fact everyone is the reason money is spending.



Controlled Variable:  My uv light and plastic square with 25 little squares.

Independant Variable: The objects that I inspected changed everytime.

Dependent Variable:  The amount of germs is what I am measuring.


  1. I am going to check what objects I can safely test with a uv light. I need to have permission from the owners that I am allowed to inspect others' belongings.
  2. I will wear gloves and a mask because we are in a pandemic and I do not know what can be on the objects I inspect. 
  3. Then I will shut the lights off, specifically the light of the room that the object is in.
  4. After I will use someone's help to take pictures and I will flash light all over the object. The pictures are how I am going to collect data.





My data shows that dirty sponges and soap dispensers have a very similar amount of germs on them.  I was assuming that dirty sponges will have many germs on them because 10 websites said that but the soap dispenser is pretty surprising. Even though I researched about soap dispensers I was still expecting something a bit cleaner. I think the reason I was really surprised was because I had seen one of the cleaners just cleaning the taps and soap dispensers so I was pretty bummed that everything is probably cleaned now but there was still so much on it. I am sure that the cleaner forgot to clean it but anyways, on the first test the soap dispensers had pretty less germs but as of the second and third attempt the sponges got cleaner and the soap dispenser got dirtier.  After all my observations I am confident that my hypothesis was pretty accurate. I think the procedure at the most part was a success but when it came to wearing safety gloves I didn't do that because I wasn't actually touching any of the objects. Something I would change about my design or way of constructing this experiment is not using the square with 25 tiny squares to calculate the percentage of germs because it was making it harder to view the germs. This did make my experiment less accurate because I had to estimate based on the picture with and without the frame.




The reason this experiment is super helpful is because right now were in a pandemic and to stay safe we need to clean and be aware of the things to stay away from. This experiment is not only helpful but it also makes people confident, a lot of people are getting impacted because of covid so if they knew how to stay more safe it really helps the fear and makes them more confident. When I tell people the objects that are more unsanitary then others know what to do about it, they can find a way to solve there fear. 

Sources Of Error

At the most part my experiment was pretty accurate. I think the plastic square with 25 boxes was the problem because in some of the pictures you can see how with the plastic square it makes it super hard to view unless your actually there and lookinng closely. Then  when you see some of the pictures without the plastic square its so mcuh clear and easty to view in the picture and in real life. SInce this happened I had to estimate the percentage for some of the pictures, what I did was based on looking at the picture with and without the plastic I would see which box had sqaure and then I would add 4%. This made my experiment less accurate but it was only about 4 pictures.


I would like to thank my sister because she helped me cut out all my images for the trifold, as well glueing.  I would also like to thank my parents for going to staples 2 times just to print my images. Second lastly I would like to thank my little brother for helping me cut out all the little germs on my trifold. Last but not least, I would like to thank Nour for taking some of the pictures from the school using her phone.