## Monday, 7 February 2011

### Geometric Stick lessons - Polygons

DD6 & DD8 worked with the Montessori geometric sticks this week.
We started with the following presentation.

Give them two connected sticks and ask them to make a shape out of it (tip keep it away from the edge of the board as they tried to make a triangle using the side of the board as a base)
If they try to make a line just explain that a line not a shape.

Give them a third line.
Once they have made a triangle ask them to label the interior and exterior and talk about it being a closed shape.

Ask if they know what the shape is called (triangle) explain that triangles are a type of Polygon.
Polygon derives from greek and means 'many corners'.
(polús "much/many" and gōnía "corner/angle". Today a polygon is more usually understood in terms of sides)
Polygons are closed figures made up of many sides all of which are straight lines.

Next we played a identification game - I made a shape and asked them to identify if it was a polygon or not.
yes
no - its not a closed shape
yes
no - it has a curved side
this last one got them - they thought it was a polygon but it isn't because the line intersects rather than connecting to only one end of two other line segments.
They then proceeded to tell me off for cheating as I hadn't explained that rule at the beginning -what a great way to make sure they never forget it :)

The Geometric Sticks are on my download page - just print on card stock or laminate - add a cork board and push pins and away you go.

We will be using these later to discuss regular and irregular polygons, brush up on shape names, discuss angles, discuss theorem of angles and lines (intersecting, parallel, horizontal etc).