M4.3.2 For the adult
Using Pythagoras
A box is 2 cm by 3 cm by 6 cm. How long is the longest stick that fits inside it?
What this chapter teaches
Pythagoras works anywhere a right angle hides: a wall and the ground, the across and up moves on a grid, or the edges of a box. The learner finds the triangle first, decides which side is the hypotenuse, then adds or subtracts the squares.
Three questions to ask
There is no one right wording. Listen for the idea.
- In a ladder problem, which length is the hypotenuse, and why do you subtract?
- How do you find the distance between two points when a coordinate is negative?
- Why is the longest stick in a box longer than the longest edge?
After the chapter, the learner can
- Find how high a ladder reaches up a wall
- Find the distance between two points on a grid
- Find the longest stick that fits inside a box
What they copy into their notebook
Spot the right angled triangle. A ladder is the hypotenuse. Across and up on a grid are the legs. In a box, d² = l² + w² + h².