## 4.2 Investigating Geometry Concepts on GeoBoards

Pre-K-2
Standards:
Math Content:
Algebra

This two-part e-example presents a virtual 11x11 pin grid and triangular grid where students can explore geometric shapes and measurements with the option of shading areas, hiding pegs, deleting segments, and moving vertices.

You can choose between two grids: rectangular and triangular .

We will refer to the pegs that the rubber band is attached to as nodes.
To begin, click on the rubber-band button . Click on a node to attach one end of the rubber band to that node. Without releasing the mouse button, drag the mouse to a second node. Release the mouse.

Next, click on the rubber band (anywhere between the two nodes). A hand will appear if you do this correctly. Without releasing the mouse button, drag the rubber band to a third node.

Continue this until the desired polygon is created.

Clicking anywhere outside of the polygon will deselect the figure.
You can also hide the nodes to investigate polygons by using the following button:
To select a single polygon, click anywhere inside of it. Options to rotate, flip, and delete will become available.

You can also color the area of a polygon by selecting it, and choosing a color from the right panel.
To delete the entire workspace, choose the delete button .

1. Using one band for each triangle, make as many different sizes and shapes of triangles, as you can on the computer geoboard. Explain to a friend the ways in which these triangles are different and how they are alike.
2. Make these figures on the geoboard:
- As many different-sized squares as possible
- Many different hexagons
- The polygon with the fewest number of sides
- The polygon with the largest number of sides you can make
- Polygons with every number of sides between the fewest and the largest