💭 If… then… because: a hypothesis at 2nd, 4th and 7th grade

The frame

Every project here gives you the same frame, with the first two blanks filled in. For the paper bridge it reads: "If I change the shape of the paper, then how many pennies it holds before it falls will go up, go down or stay the same, because…"

The because is the part you write yourself. It's your reason, and it's allowed to be wrong. A guess with a reason is a hypothesis. A guess with no reason is just a guess.

Stuck on the because? The project page gives a nudge, never the answer: "Think about which way the paper is standing when the pennies press down on it."

At 2nd grade

A 2nd grader keeps it short and says it out loud first. A grown-up can write it down, as long as the words are the child's.

"If I fold the paper, then it will hold more pennies, because it feels stronger when it's folded."

That's a real hypothesis. It names the change (folding), the thing to count (pennies) and a reason from something the child noticed with their own hands.

At 4th grade

A 4th grader names every level and says which one will win. They also know they'll work out the mean of three tries, so the hypothesis can be about the means.

"If I change the paper from flat to folded like a fan to rolled into tubes, then the tubes will hold the most pennies, because a tube is hard to squash from the top."

This one is easy to check. After the test, look at the three means and see whether the tubes came out on top.

At 7th grade

A 7th grader says how much, and uses a science idea for the reason instead of a feeling.

"If more of the paper stands on its edge, as in a fan or a row of tubes, then the bridge will hold at least twice as many pennies as flat paper, because a sheet standing on its edge is much harder to bend than one lying flat."

Saying a number (twice as many) is brave, and it makes the conclusion sharp: the means either show it or they don't. A 7th grader also plans a second test. The project's Going further line gives one: "Change a second thing: test the fan shape with one, two and three sheets stacked, and graph how the strength grows."

What a judge listens for

At any grade, a judge wants the hypothesis in your own words, written before the test and not changed after it. Here's what fairs usually expect from the question at each age:

• 1st–3rd: One thing changed, one thing counted or seen.
• 4th–6th: One thing changed, one thing measured with units.
• 7th and up: One thing changed, then a second variable.

Print the hypothesis sheet to write yours. If it turns out wrong, read when your hypothesis is wrong. It happens to real scientists all the time, and it makes a good board.