2-min Warm-up — True or False? Circle one.
A line segment has 2 endpoints. T / F
A ray goes on forever in both directions. T / F
A point shows an exact spot. T / F
A line has 2 endpoints. T / F
A right angle makes a perfect square corner — like the corner of a book or a door. We mark right angles with a small square. □
Right angle
(square corner)
Smaller than a right angle
Bigger than a right angle
Estimate First! Look with just your eyes: is each angle a right angle? Write your estimate, THEN check with the corner of an index card.
My estimate (yes/no):
Card check (yes/no):
My estimate (yes/no):
Card check (yes/no):
My estimate (yes/no):
Card check (yes/no):
My estimate (yes/no):
Card check (yes/no):
How many right angles does each shape have? Mark each one with a small □.
Square
right angles
Rectangle
right angles
Triangle
right angles
Circle
right angles
Two Ways to Check — Show two different ways to test if the corner of your desk is a right angle.
Ideas: corner of paper, corner of a book, fold a circle twice...
Strategy 1:
Strategy 2:
Was it a right angle?