Here’s a fun water experiment to get kids interested in science.   And the supplies are simple – drops of water on a penny.   Kids Activities Blog loves hands-0n projects like this that use simple supplies from around your home.   Have fun! You may have heard the old saying “How many angels can dance on the head of a pin”. Well, my son and I decided to find out how many water droplets can sit on the head of penny. We gathered all the supplies we were going to need to find out exactly how many drops would fit.  We needed a water dropper or pipette, a penny, a measuring cup filled with water, and a plate to hold the penny.

water experiment

Water Experiment

Before we got started we discussed how many drops we thought could fit on the penny.  My son predicted fifty and I guessed about fifteen.  Then we talked about what size drops we thought we would need to add to the penny to get the number of drops we had guessed. We decided that we would need to add really big drops to have fifteen. Really tiny drops would help us get closer to the fifty drop my son had guessed. My son filled the pipette with water and slowly started dropping water on the penny. As you can guess he was trying to make the smallest drops possible.

water on a penny experiment

Water on a Penny

At this point he had about nine drops on the penny and the penny was looking almost half way filled. I asked him if he wanted to change his estimate and he did not. He stood firm with his guess of fifty. I did notice the drop got a tab bit smaller as he continue to drop water on the penny.  

water experiment for kids

  By the time I took the picture above he was at  nineteen  drops and it was really looking we weren’t going to get to fifty.  

water experiments

When we reached the twenty fourth drop, we both realized the water was going to overflow. It was then and only then that he wanted to change his guess to twenty five. Sometimes you have to do an experiment to see what will really happen. I bet if we tried this experiment again he would guess a number closer to twenty five.  In fact I think he probably would guess twenty five exactly.

More Kids Activities

Kids love to play with water so why not add some learning fun with some water experiments.   This water on a penny experiment is just one of many great ideas.   Here are a few more kids activities working with water:

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  1. This is a great way to get kids excited about science! What is great about this activity is that it can be adapted to any level. I use a version of this activity with middle and high school students to teach about extraneous variables. Having several people perform the activity, and then have them talk about who is “right.” They always want to say their answer is the “right” one. So I rephrase the question to say, how could a person “cheat” to get more drops on the penny. This allows them to see that there are lots of ways that impact the data. Then we come up with a list of ways to “make it fair.” This is when I introduce the idea of constants within an experiment! We also figured out that conducting the experiment several times and then averaging (finding the mean) is a way to collect meaningful data! It is also a great lesson on observation. Kids can’t help but see that the water is forming a huge bubble on top and even is falling over the edge. I like to have them get at eye level with the penny so they get the full effect! If you want you can then open it up for a discussion of water tension!

    The dropper you used was much bigger than the one my kids use. We were getting numbers like 50 and higher. It really kept the suspense high! Great post!