Triangles

Recently one of my older students wanted to work with the detective adjective game [shown in the picture at the end of this post] which is a grammar activity but the child must know the names of all the triangles to work with it. Last term she tried to learn the triangles by doing a three-period-lesson with the geometric cabinet, but she couldn't get it and quickly lost interest. After reading the geometry manual at Cultivated Drama I decided to teach this differently.

I began by asking the child to construct three triangles with the geometric stick material. The first triangle was made from 3 pieces of the same size, we spoke about how all the sides are equal. Then I asked the child to construct a triangle with 2 sides the same and one side different. Thirdly she made a triangle with all the sides different. We then did a three-period -lesson and after the final period I questioned her 'Why is this an isosceles?', 'Why is this a scalene?', 'Why is this an equilateral?'. We then labelled them. To ensure that she fully understood, I got her to draw the three triangles in her book, write the names and a description for each.

The next day I checked if she could remember the names for each triangle. Next we did the same thing for the angles. We used the geometric sticks and placed a pencil in the end hole and drew three angles. We did a three-period-lesson, labelled them and recorded them in her book.

We then got out the geometric cabinet triangle tray. She sorted the triangles according to the names and then sorted those by the angles. She did it well!
You can't really see the labels in this picture but the top labels say, 'right angled', 'acute angled' and 'obtuse angled'. The labels on the right say 'isosceles triangle' and 'scalene triangle'.
The next day I asked her if she wanted to work with the triangle terminology cards. First she matched them with the control cards, then she matched them without. Here is a link for these cards I made if you want to download them.
Next she made a triangle chart all by herself. She traced around all the triangles in the geometric cabinet and cut them out from blue paper. She stuck them on her chart in the correct places.

Finally she was ready to work with the 'Detective Adjective Game'. She was thrilled!

I love how children in a Montessori classroom can work day after day, hour after hour to achieve a certain goal they have without giving up. This story is just one example of the many that happen daily in a Montessori setting.