Sink or Float: Easy Orange Experiment

Sink or Float: Orange experiment
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Spending time with my nieces is one of my favorite hobbies. I think it is so good for people to spend time with kids; it reminds us of the importance of being silly and having a sense of wonder! Lately, a lot of my nieces’ favorite activities have been science experiments. I have been on the quest for fun but easy science experiments for kids. I found just that with this orange sink or float experiment. It was a hit!

Required materials

  • An orange
  • Water
  • A big bowl/cup/vase

Orange sink or float science experiment

This is a very simple science experiment, just a few easy steps. It went so fast, and we were so absorbed into the experiment that I even forgot to take pictures.

Step 1: Give a brief explanation about buoyancy and density

Before starting the experiment, you should take a couple of minutes to discuss buoyancy and density. This way, they can think about it (and you can talk about it) while doing the experiment and making your predictions.

You’ll want to keep the scientific explanation brief and simple, or the kids won’t listen/understand.

The points we covered:

  • Buoyancy is the tendency of an object to float.  
  • Something only floats if its density is less than the density of the water. An object’s density is its mass relative to its volume. An object with a lot of matter in a small space has a high density. This part got confusing, but they seemed to understand better when I skipped the terms, and we talked about a shoebox of rocks being denser than a shoebox of feathers.

Step 2: Fill your chosen container with water

We used a big bowl, but any container that you can fit an orange and see it float or sink will work.

Tip: After we had already done the experiment, I saw that Cool Science Experiments Headquarters used two containers and oranges so you can simultaneously compare. I think this is a good idea. If we do this again, I’ll use two containers.

Step 3: Make your predictions

Ask the kids whether they think the orange with the peeling will sink or float?

They said that it was heavy, so they predicted that it would sink.

Step 4: Put the unpeeled orange in the water

They were amazed to see it float on the water. Honestly, I was pretty amazed too! I had never thought about how porous an orange peel is before.

Step 5: Peel the orange and make your predictions if it will now sink or float

They thought it was strange for me to be asking for another prediction since we just saw that an orange floats. They both predicted that it would float.

Step 6: Put the orange without the peel in the water

They were so confused about why it now sinks.

The science behind this:

The orange’s density with the peeling is less than the density of the peeled orange because while it is bigger (has more volume), its mass doesn’t change much because the peel is full of tiny air pockets.

These pockets of air increase the orange’s buoyancy, making it float. I described the trapped air in the peel as their floaties in the pool that help them float. This seemed to help them understand.

Try other items

I lost Kenzi’s attention after the explanation (too many other things she could be doing), but Quinn was so curious! She started grabbing other items around the house and asking about their density.

We put various items such as pens, rocks, erasers, a checkers piece, etc… into the water to see if they would float. We would make predictions each time (we were pretty good guessers).

Checking if other household sink or float

Her favorite part was that the hair ties would float at first and then sink after they got waterlogged. She found that amazing!

We ended up spending a long time testing items. It was a big hit! You can’t beat an experiment that is fun, educational, and easy.

Pin this for future reference or share with your friends to give them an idea for an easy experiment that they can do too!

For other easy activities to do with kids, check out ballon tennis.

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