Oh the scientific method! Such a structured way to exploration but so helpful when taking on a big scientific project. Scientists and researchers use this method when trying to answer questions about our world. Following the scientific method allows researchers to have a guide that helps them organize all the information. Because let’s face it, nowadays the information at our fingertips is so huge! With this STEM experiment, you can help your children get an understanding of using the scientific method in a fun and educational way.
**Check out our Simple Science Project For Kids: Float or Sink for a simple play-based version of the Float or Sink experiment! Perfect for younger kids or if you are looking for a less structured activity.**

Having a tool like the scientific method is very useful. And introducing it to your kids will help them with problem-solving and analytical skills. It will give them a way to structure their thoughts when problems arise. It also shows them to take their time to think about the problem and analyze different perspectives before choosing the best solutions.
Some Background Information
The scientific method is used by scientists to structure their research and make the process of discovering something more efficient and effective.
The steps to the scientific method are the following:
- Question
- Research
- Hypothesis
- Experiment
- Analyze
- Conclusion
As you can see, there are many steps before starting any experiment. By researching and writing down your hypothesis first you will be able to set up the perfect experiment to answer the question. You will also have some background knowledge that will help you when doing the experiment.

STEM Experiment: Let’s find out the Answer to…
The Question
So here is a question for your children:
Why do you think things float or sink?
They probably have some ideas and answers for this. Encourage them to write down their original thoughts so that you can compare them once you are done with the STEM experiment.
Here you can find a free printable to fill out as the experiment goes on.
Time to Research
Research is usually done by reading and reading and more reading of scientific papers, journals and relevant material. We are not going to do this 🙂 We will move the research along by asking our kids some questions. So let’s get your kids brain to work a bit:
- Think of objects that float/don’t float, what are they made of? How big are they?
- Do you float in water? Can you make yourself float more or less? (By filling your lungs with air and holding your breath you will float more)
- Show them a list of materials, do you think materials matter?
- Show them different sized objects or images of objects, do you think size matters?
- What other things do you think affect the ability of an object to float or sink?
Write down a Hypothesis you want to test
Now that you have brainstormed about why an object floats or not you can make a hypothesis or more than one! But first, what is a hypothesis?
- A hypothesis is an idea or explanation for something that needs to be proved
- A hypothesis tries to answer the question of your research (in this case, why do things float or sink?)
- A hypothesis is proved through experiments and testing
Some ways you can express your hypothesis:
- Things made out of _______ float/sink
- Things that are ___________ float/sink
- Floating depends on ______________
Time to test those Hypotheses
Once you’ve made a hypothesis, ask your child how you could test it. Here are a few examples of experiments you could do with them but feel free to come up with your own!
First step in any experiment is to gather the materials you are going to test and any tools you might need. For any experiment you are going to need:
- Objects to test (different sizes, materials and shape)
- Water, in a bucket, in the sink, in the bathtub, in a small outdoor pool
- Paper and pencil to write down your findings
Ways you can experiment and make your children think about the hypotheses:
- Categorize the objects you have collected and test their floating ability by pairs:
○ same material, different size
○ same material, different shape
○ same size, different weight
- Get plastic containers and fill them with different materials and test the floating capabilities, for example:
○ empty container
○ container filled with cotton (what happens when cotton gets wet?)
○ container filled with sand
○ container filled with water
○ container filled with sticks
○ container filled with coins
○ container filled with stones
- Do the same with a glass container
There is a list of materials and object ideas in the guide for inspiration. Let them experiment and play 🙂 there is no rush to finish the activity! Don’t forget to write down your findings so you can analyze them later!
Let’s analyze those Resultats
Now it’s time to look back on your STEM experiment and the results to see if your hypothesis was correct. You can ask the hypothesis back in question form and see if the results support it! Other questions you can ask to discover why certain objects float:
- Does wood/plastic/metal/stone float?
- Does shape or weight matter?
- What containers could float? Which ones would sink? What was inside of them?
Conclusion Time
So did you find out why things float? Did you test your hypothesis? Did you get some fun ideas about other things you could test with this method? Did more questions pop up as you experimented? Welcome to the STEM world! The questions never end 🙂 and this is oh so important for your children to experience. How to answer questions using the scientific method is a must in the STEM world. If you want a more detailed answer to why things float you can download the printable guide, there is an explanation at the end. But I’m sure that you will have a pretty good idea about the answer from all that scientific experimenting you will do 😉
So to finish up the activity you can talk about what you discovered and if there are more things you would like to research together. If you have any topics you would like me to cover just comment below and I’d be happy to write a post about it in the future. I hope you enjoyed this activity and had fun experimenting and discovering how our world works.
For more information about STEM and how to transform your STEM activities at home, check out these posts:
Check out other fun STEM activities to sneak in some STEM learning:
- STEM activity: Build a pyramid and learn about shapes
- STEM project: Engineer a house out of natural materials
- STEM challenge: The Tower of Random Things
- STEM water play: 8 fun activities to try this summer
- STEM Road Trip Experiment
Happy STEM learning!
