Before you touch anything, write down the question, the one thing you will change, the things you will hold still, and what you will measure. Deciding afterwards is how an investigation drifts into whatever happened to be easy.
Step 1: Something to Notice
Watch first. The explanation comes later.
Two students get the same numbers. One writes "the block went further". The other writes what they changed, what they held still, and what it means. Only one of them has done science.
What has the second student got that the first has not?
Step 2: Find Out
Question: does a bigger pull make the block travel further in 5 seconds? Plan it, then run it.
Step 1 — Predict
To test whether a bigger pull goes further, which must you hold still?
Choose what you think will happen. You cannot see the experiment until you do — guessing first is what makes it worth watching.
Step 3: So Here Is Why
Now the explanation, after you have seen it happen.
Run it more than once
One result could be a mistake. Three that follow a pattern are evidence.
Then make a claim
A claim is a sentence that answers the question. Not a number — an answer.
Claim A sentence answering the question you asked.
Back it with evidence
Evidence is your actual measurements, plus the list of what you held steady. The second half matters as much as the first: numbers from an unfair test are not evidence for anything, however carefully they were written down.
Evidence The measurements you actually took.
And join them with reasoning
Reasoning explains why the evidence supports the claim. This is the part everybody skips, and it is the part that matters.
Reasoning The explanation of why your evidence supports your claim.
Plan before you start
Write down the question, what you will change, what you will keep the same, and what you will measure. Doing that first is what stops the investigation from drifting halfway through.
Argue for what you found
State the claim, give the measurements that support it, and explain why those measurements support that claim. A result without the reasoning is only half an answer.
Step 4: A Common Mistake
Lots of people think
“Once you have the result, the investigation is finished.”
Step 5: Why Three Runs and Not One
The same idea somewhere new.
One measurement could be a mistake and you would never know. Three that follow a pattern are much harder to argue with — and if one of the three disagrees with the others, that is worth knowing too.
Step 6: Think It Through
Practice makes it stick.
The Write-Up
Problem 1 of 1
A student writes only "it went 100 cm". Which part of the argument is that?
Building an Argument
1 of 4
How many times should you run a test before trusting the result?
2 of 4
Match each part of an argument to what it does.
Tap a card on the left to start.
3 of 4
Which part of an argument do people most often leave out?
4 of 4
Put the steps of an investigation in order.
- 1Run it several times and record the numbers
- 2Make a claim that answers the question
- 3Explain why the evidence supports it
- 4Decide what to change and what to hold still
Step 7: Quick Check
Show what you know.
Question 1 of 1
What is reasoning?
Step 8: Explain It in Writing
Claim, evidence, then reasoning.
The question
Using your three runs, write an argument answering the question: does a bigger pull make the block travel further in 5 seconds?
Evidence you can use
- With a pull of 2 the block had gone 50 cm after 5 seconds.
- With a pull of 4 it had gone 150 cm.
- With a pull of 6 it had gone 250 cm.
- The surface was set to wood for all three runs.
- Friction pushes back against the pull, and what is left over moves the block.
- One run could be a mistake; three that follow a pattern are harder to argue with.
Words to usepullsurfacedistancethe samechangedunbalanced force
Fill in all three boxes. The reasoning box is the one that matters most.
What You Found Out
- Plan what you will change and what you will hold still, before you start.
- Run it at least three times.
- A claim answers the question. Evidence is your measurements.
- Reasoning explains why the evidence supports the claim.