OER4Schools/Exploring polygons

ICT activity exploring polygons with Geogebra

As we mentioned above, the upcoming unit is on enquiry-based learning, and will feature a number of ideas for extended project work. In this section, we are looking at Geogebra, an application that is well suited to support interactive mathematics applications. We first explore the use of Geogebra to draw polygons.

Working in pairs with a laptop (11 min). Start up a laptop and log in. Locate and start the Geogebra application. Draw some polygons. If you need help, watch the following video:

When you have drawn some polygons, see whether you can draw some "crazy" polygons with lots of points, or whether you can move vertices (the points where sides meet), to make other polygons, including

• polygons where some of the sides cross (“self-intersecting” or “complex” polygons),
• polygons where the sides do not cross (“simple” polygons),
• polygons where some angles or sides are the same.

Educator note

You need to be watching the time, as this activity is very extensible. For further ideas, you could have a look at the Wikipedia article on polygons. You could also have a look at the Shape and Space collection at the UK National STEM centre. In particular at these two documents

• http://www.nationalstemcentre.org.uk/elibrary/file/9892/mm_shape_space_06.pdf
• http://www.nationalstemcentre.org.uk/elibrary/file/9898/mm_shape_space_12.pdf

have got some interesting questions in them, which you could use, including questions for developing your mathematical vocabulary (such as: “This shape has a right angle.”, “This shape has four vertices.”) as well as some talking points, such as

• If you cut a rectangle in half, the perimeter will be half its original length.
• A square and a rectangle both have the same perimeter. The square has the greater area.
• Draw two rectangles. The one with the greater area will also have the greater perimeter.

We will explore ideas like these further in the unit on enquiry.