## Friday, May 4, 2012

### Paper Frisbee Geometry

Sunday A (age 11) made a paper frisbee, as part of a verse go-along activity, in her Sunday school class.  It's a very good frisbee, and still processing the whole higher math debate, I thought it could probably be used for a nice geometry lesson, too.

To make one, you start out by trimming two sheets of paper into 8''x8'' squares.

Divide, and cut each of the squares into four, 4''x4'' squares...

...for a total of eight squares.

Fold each of the squares in half, turning them into rectangles.

Fold the rectangles in half, short sides together...

...and unfold them, so you have eight rectangles, each divided into two squares.

With the fold at the top of the rectangle, take the bottom left corner and fold it to the top right corner of that square...

...creating a shape made of a square and a right isosceles triangle.

Now, fold the top right corner of the square down to the bottom left corner...

...to form a parallelogram made of two right isosceles triangles.

A piece of tape can be placed between the two triangles to hold them in place.

Once you have folded all eight squares into parallelograms...

...you can begin forming an octagon by placing the closed corner of one parallelogram  into the open side of another...

...to from a 135° angle.

You can double check, that you need a 135° angle, with the formula for angles of a regular polygon:

s - 2 * 180°/s = the degrees of the angles of regular polygons, where s = the number of sides of the polygon.

In this case that would mean the angles should equal 8-2*180°/8 or 135°.

You can double check the angle with a protractor if you are uncertain...

...or eyeball the angle.  If this is 90°...

...and half of 90° is 45°...

...then the two together look to be about 135°.

Or, you could be really clever and just add up the three 45° angles from all the isosceles right triangles placed together.  Either way, once you've determined you have a 135° degree angle, continue adding sides in the same way...

...taping the pieces together as you go...

...finally slipping the last piece into the first...

...to close the octagon...

...for a very nice frisbee...

...with a geometry lesson thrown in, just for fun.

Now, if we just had a better grasp of calculus, we could probably even complete a throw.

It's great to be a homeschooler.

#### 9 comments:

Sheltie Times said...

Throw in some Physics and you'll be fine. :)

Natalie PlanetSmarty said...

Now, this would be an excellent math lesson for middle school :)

An Almost Unschooling Mom said...

Raising a Happy Child - Yes, but the math isn't really necessary for making the toy.

Joyful Learner said...

That is so cool!

Fairion said...

Looks like tons of fun. We are going to try it. Maybe even with a baby bit of geometry thrown in.

Phyllis said...

I love it!

Christy Killoran said...

That is a cool frisbee.

Ticia said...

I never remember how much of a visual learner I am until I triy to translate the words I read but the picture makes great sense

This has very little to do with your post but I suddenly realized it again reading this because the pictures were so perfect

Gabriel Lorenzo said...

I love making the frisbees! I got the steps all correct!