Grade 3: polygons and right angles

Bonjour!  We have started a unit on Geometry and are learning about polygons and right angles.  The polygons are shapes that have many sides.  One big idea is that the polygons are named for the number of sides they have, regardless of what they look like.

Polygons (Les Polygons)
triangle (un triangle) - 3 sides
quadrilateral (un quadrilatère) - 4 sides (square, rectangle, others)
pentagon (un pentagone) - 5 sides
hexagon (un hexagone) - 6 sides
heptagon (un heptagone) - 7 sides
octagon (un octogone) - 8 sides

These are the main ones we will focus on in this unit.  Please review these terms at home for practice.

Right Angles (les angles droits)
We are learning about what angles are, and how to tell if an angle is a right angle or not.  At this point, we are NOT using degrees for measuring (i.e. a right angle is 90 degrees). This is how I've explained it so far:
-an angle is a corner of a shape
-a right angle is a corner that is EXACTLY like the corner of a square
-if it's not exactly the same, the corner can be SMALLER or BIGGER than a square

If you see examples of right angles around the house or town, please point these out to your student, as this concept is still very new.

This week we have been working with geoboards to try to make the different polygons and trying to make them with as many or as few right angles as possible.  Geoboards are plastic square boards with pegs in them, that elastic bands fit around to make the polygon shapes.  Here is a photo of one, the example has a pentagon on it (5 sides), and contains three right angles (corners that are the same as the corner of a square).

  In this shape, the top left, bottom left, and bottom right corners have the right angles.  The other two corners are 'bigger' than a right angle because in you put a square in the corner, there will be extra space left over.

Happy shape and angle hunting!