This is part of my 15 Minute Focus series. We use a sink/float experiment as an introduction the the basic steps of the scientific method. You coud also do a similar lesson with “is it magnetic?” or any other question that’s easy to test.

Objective: children can describe some of the steps in the scientific process.

Supplies

• Container of water, paper, crayon or colored pencil, towel
• A “mystery bag” full of miscellaneous items – some that everyone expects to float, some that everyone expects will sink, and some where it’s hard to guess what will happen (my random assortment that day was: a foam letter, a metal key, a plastic animal, a cork, a sponge, a rock, a stick, a shell…)
• lyrics for a Scientific Method song – choose the one you like best – in my example below, I use the one with the tune Drunken Sailor

Activity

This activity weaves together the concept of the day, the song, and a hands-on activity.

Talk a little about scientists – who they are, what they do. Then explain that they follow a process to learn about the world. It’s called the Scientifitc Method, and we’re going to learn it and practice it today.

Sing first verse of song: “first we think up lots of questions.” Then ask if they have any questions about how things work (they might not).

Then talk about how scientists observe with all their senses  – what does that mean? Sing that verse.

Tell them that you are going to pass around the mystery bag. Each child will reach in, touch something and describe it without looking at it. Then take it out. Model for them how to do this. (Note: four year olds might have a hard time not looking…) Then pass it around and have them each do the activity. [Alternative: if you have more than 8 kids, you probably want to just pass the bag around and have each kid take an item out and pass it along. Skip the “describe it aloud” portion.)

Then ask them all to draw a picture of their item. Talk about how scientists write things down to remember what they observed and to share those observations with others.

Explain that when we have a question, we can guess at what the answer is. The scientific word for an educated guess is hypothesis. Sing hypothesis verse.

Intro today’s question – will it sink or will it float? Hold up one object and ask them to make a guess – do they think it would sink or float? Why do they think that?

Then tell them we’re going to do an experiment. Sing “do an experiment” verse.

Tell them we’ll test each of their items in the bowl of water. For each item, you’ll ask them to make a hypothesis and predict whether it will sink or float. Tell them to show thumbs up if they think it will float thumbs down if they think it will or sink.

Then test their items one at a time., and write the results. (Note: It’s hard for them to wait their turn!) Show results, and sing “record results” verse. Ask them to share something they learned about what kinds of things float, and what things sink.

If there is a lot of time remaining, you could read a book. If there’s a little time remaining, they’ll happily play sink and float with their items till time is done.

Then sing “hooray we learned something” verse.

Optional Extensions

Books to go with this lesson: for non-fiction: Scientists Ask Questions by Garrett, which introduces science tools and the scientific method, or for fiction with a lesson, I love Charlotte the Scientist Is Squished by Andros, which is an engaging story for age 3 – 6 and does a a nice job of reviewing the steps of the scientific method. Here is a YouTube read-aloud to preview it.