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Bike Shop 3-5 / Week 01 / Friday
5/6
Week 01 · Meet the Bike

Friday

Brakes and the whole team
// A system of parts with jobs
⏱ about 15 min

Friday: Brakes and the Whole Team

Rocket wants to carry his shop notebook on the bike. "I will tape it to the handlebars!"

Raven frowns. "What do you notice? Your hands and the brake levers are there."

Rocket looks again. "Oh. The notebook would get in the way."

Nova hovers nearby. "Good engineers name the problem first," she says. "What must your idea do?"

The brakes

Brake levers sit on the handlebars.

A rider squeezes a lever to put on the brakes.

On many bikes, the brakes press pads onto the wheel rims.

That slows the bike down to a stop.

We will study brakes closely in week 7.

A rider squeezes a lever to use which part?
WHY THIS EXERCISESqueezing the brake lever puts on the brakes.

Parts work together

In a system, each part needs the others.

A chain with no back gear cannot turn the wheel.

A wheel with no tire cannot grip the ground well.

When one part has a problem, the whole bike may not work right.

WHAT IF A PART IS MISSING?
  • Read the question.
  • Tap your answer.
The chain falls off. What stops working?
The fork is loose. What gets hard?
What should happen with a bike that has a problem?

Engineers name the problem

Rocket has a problem: how to carry a notebook on a bike.

Engineers list what a good answer must do. These are criteria.

They also list the limits they must work within. These are constraints.

Rocket's problemNotes
Problemcarry a notebook on the bike
Criteria (must do)keep the notebook dry; stay out of the rider's way; hold on tight
Constraints (limits)use things from home; a grown-up helps attach it; one weekend to build
Idea for RocketDoes it meet the criteria?
Tape the notebook over the brake levers.?
Put the notebook in a bag strapped behind the saddle.?
Hang the notebook from a string near the spokes.?
WHY THIS EXERCISEAn idea must meet the criteria, like staying out of the rider's way.
HOW ENGINEERS START
  • ?List the criteria.
  • ?List the constraints.
  • ?Name the problem.
  • ?Think of ideas.
WHY THIS EXERCISENaming the problem and its criteria first helps ideas work better.
Try it
Think of one more bike problem a kid might have.
Write it in your shop notebook.
Under it, list two criteria and one constraint.
Safety first
Any new part on a bike is attached by a grown-up.
Nothing may touch the brakes, chain or spokes.
In your shop notebook, draw one idea for carrying Rocket's notebook. Label how it meets each criterion.

Fantastic thinking, engineer! Tomorrow is Bike Shop Day: a family parts tour.

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