## Friday, September 27, 2013

### From Circles to Symmetry - More Geometry projects!

Another collection of geometry projects, these run the gamut of excersizes for symmetry, to circles, triangles and quadrilaterals.
Symmetry - https://app.box.com/s/ygce0jmdjiiotuohuyys
The long black line can be moved around, as can the images! Using the black line, students can divide the images in half and try to get a better sense of if the image is truly semmetrical or not. One or two of them are tricky to see! And make sure you assure the students that yes, one of the images has NO lines of symmetry. (It's a sneaky one)

Circle Area - https://app.box.com/s/vz06ht16gxjbokehy3zv
With three squares layered on top of a circle with bases the length of the radius, students can begin to visualize why it is that the area of a circle is equal to the radius multiplied by pi. Once the bits of the squares that don't fit into the circle are moved around to the empty quadrant, it becomes clear that there's actually enough room for three radius lengthed squares, plus a bit extra. The second slide is already assembled to show the relationship, in case students become frustrated with dragging all the little bits around.

A few problems where students can explore the relationship between various different types of quadrilaterals. By dragging the appropriate shapes into place, students can demonstrate that a square is a rectangle, which is a parellelogram, which is itself a regular old quadrilateral.

Triangle Area Slider - https://app.box.com/s/ssj0gpwjspg81526w44l
Like the circle area problem, here students can begin to see how just because a triangles dimensions might change, if it's base and height are the same, the area will be too. The Triangle in the centre comes apart into several peices, which can be moved over top of other triangle outlines. While it might not be exact, it does give a good impression of the way that area doesn't always  change even when the angles in a triangle do.

Triangle Sorter - https://app.box.com/s/ubjddfhzbb8pdkmr5bkv
A good activity for sorting and learning the difference between acute, right, and obtuse triangles. Using a right angle, students are challenged to sort the triangle sinto the correct bins.