Euclid in The School of Athens by Raphael Sanzio |

We practiced squaring numbers 1-10 on the whiteboard.

Then I asked them if they could find three numbers in a row where the first number squared plus the second number squared equals the third number squared.

They found that 3, 4 and 5 squared fit that description.

Knowing that in advance, I had cut out squares in 3, 4 and 5 inches. I gave them to them and asked them to form a triangle out of them.

Which, of course, led us to a discussion of Pythagoras, which we had learned about before.

Which led back to a discussion of angles in triangles.

And so we measured some more angles, this time on triangles. I had them keep track of the angles they were measuring.

And after a bit of this, they discovered that all the angles of the triangles always equaled 180 degrees.

Well, actually they didn't get it at first because they didn't always add up to exactly 180; it is easy to get the measurement off a degree or two, but when they were off a bit, we measured again, and then got 180.

And all this led to a discussion of the differences between the different triangles.

And so we made little books with pages with the different triangles.

And, following the example at

*Daily Life of a Mom*, we made these interactive pages.Right angle triangle, showing the other 2 angles make a right angle too. |

Equilateral triangle, showing all sides and angles are equal. |

Isosceles triangle, showing two sides are equal. |

We could have also done an activity I saw at

*Free Play Life*in which the kids made the different angles with their hands, arms, fingers and even, getting together, their whole bodies, but they didn't seem to need it. I always try to have more activities planned than I could possibly do, so if one doesn't work, we can glide on into the next one without any problem, or in this case, if we don't need one at the end, we can just not do it, or save it as a warm-up for next time.
If you or your child likes worksheets, here are some that go along with this lesson.

*Jimmie's Collage*also has a similar lesson on angles.

I remember thinking the 30-60-90 triangle was one of the coolest things to learn about.

ReplyDeleteVery clear - very nice!

ReplyDeleteI know who I will be turning to when we get to higher math! Thanks for sharing!

ReplyDelete