"Why did the ice cube melt so fast?" "Because it's magic!" Young children often answer "why" questions with whatever comes to mind first. That's natural. A wonderful next step is learning to give a reason that can be checked: "I think it melted fast because it was in the sun."
That kind of guess is called a hypothesis. It sounds like a big word, but the idea is simple, and children can start practising it from around age 5 or 6. This article shows how.
What a hypothesis is
A hypothesis is:
- A guess about what will happen or why something happened,
- with a reason,
- that we can test.
"It's magic" isn't a hypothesis, because there's no way to test it. "It melted fast because it was in the sun" is a hypothesis: we can put one ice cube in the sun and one in the shade and see.
The "I think… because…" sentence
The easiest way to build this habit is a simple sentence frame:
"I think ______ because ______."
| Just a guess | A hypothesis |
|---|---|
| "The big ball will win." | "I think the big ball will roll further because it's heavier." |
| "The plant is sad." | "I think the plant is drooping because it hasn't had water." |
| "This one." | "I think this paper towel will soak up more because it's thicker." |
Model it yourself: "I think it will rain later because the clouds are getting dark." Children pick up the pattern quickly when they hear it often.
A first test: where does ice melt fastest?
This simple test works well at home.
- Take three ice cubes of the same size.
- Choose three places, such as a sunny windowsill, a shady shelf and a plate in the fridge.
- Ask for hypotheses: "Where do you think the ice will melt fastest? Why?"
- Check every ten minutes and draw or describe what you see.
- Compare with the hypothesis: "Was your idea right? What did we find out?"
Keep the test fair: same size cubes, same kind of plate, checked at the same times. Only the place changes.
When the hypothesis is wrong
A wrong hypothesis isn't a failure. It's how scientists learn.
- Celebrate the surprise: "Interesting! It didn't happen the way we thought. Why might that be?"
- Make a new hypothesis: "Maybe the plate in the sun was hotter, not just the air."
- Test again if you can.
Children who learn that being wrong is part of the process are often more willing to try ideas, in science and everywhere else.
Everyday puzzles to form and test ideas
Hypotheses aren't just for experiments. Everyday life is full of chances:
- The drooping plant: "Why do you think it's drooping? How could we test that?" Water it and check tomorrow.
- The toy car: "Why does it roll further on the kitchen floor than on the carpet?" Try both and measure.
- The paper towel: "Which one soaks up more water?" Dip strips of different towels into coloured water.
- The missing sock: "Where do you think it went, and why?" Check the places your reasons point to.
The question to keep coming back to is: "How could we find out?"
In Dologi, "Guess the rule" puzzles in the Logic topic show a group of things that follow a hidden rule; children form an idea about the rule (same colour? same number of sides?) and use it to pick the one that belongs.
In short
- A hypothesis is a guess with a reason that can be tested.
- Practise the sentence "I think… because…", and use it yourself.
- Try a fair first test, such as where ice melts fastest, and compare results with the hypothesis.
- Treat wrong hypotheses as discoveries, and keep asking "How could we find out?"
Read more: The sink-or-float experiment: guess first, then test