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Science Launch G3 / Week 04 / Tuesday
2/6
Week 04 · Magnet Inventions

Tuesday

Criteria and constraints
// Solving problems with magnets
⏱ about 15 min

Tuesday: Criteria and Constraints

Rocket sketches a giant grabber with ten magnets and a motor. "It will grab everything!" he says.

Raven smiles. "What do you notice about our supply box? We have one magnet."

Nova projects a list in the air. "Write what the grabber must do," she says. "Then write your limits."

Rocket laughs and erases half his sketch.

Two engineering words

Criteria are the things a design must do to be a success.

Constraints are the limits on a design. Limits can be the materials you have or the time you have.

Engineers check both before they start building.

The paper clip grabberCriteria or constraint?
It must lift at least 3 clips at once.criteria
It must reach the bottom of the jar.criteria
We can use only one magnet.constraint
We have 10 minutes to build.constraint
StatementIs this a constraint?
We can only use string, tape, a pencil and one magnet.?
The grabber must lift 3 clips.?
We must finish before dinner.?
The grabber must not drop the clips.?
WHY THIS EXERCISEMaterials and time are constraints. Things the design must do are criteria.
CRITERIA OR CONSTRAINT?
  • Read the question.
  • Tap your answer.
The grabber must reach the bottom of the jar. Is that a criterion or a constraint?
We can use only one magnet. Is that a criterion or a constraint?
What a design must do: ____
Limits on a design: ____

Sort a new list

Raven wants to design a key hook for the door. Here is her list.

It must hold 3 keys. It must be easy to reach. Those are criteria.

She can use only tape, a magnet and a card. She has 20 minutes. Those are constraints.

RAVEN'S KEY HOOK
  • Read the question.
  • Tap your answer.
It must hold 3 keys. Criterion or constraint?
She has 20 minutes. Criterion or constraint?
She can use only tape, a magnet and a card. Criterion or constraint?
PLAN BEFORE YOU BUILD
  • ?Say the problem clearly.
  • ?List the constraints.
  • ?Sketch an idea.
  • ?List the criteria.
WHY THIS EXERCISEEngineers know the problem, the goals and the limits before they design.
Time and materials are examples of what? Type one word.
WHY THIS EXERCISEConstraints are limits, like how much time or which materials you have.
Try it
Pick a simple problem, like keeping a door from swinging shut.
Write two criteria for a solution.
Write two constraints.

Great job sorting! Tomorrow you build and test your own paper clip grabber.

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