Students begin identifying geometric attributes at a fairly early age. Our 1st Grade teachers introduce vertex, edge, and face. Still, it seems that kids have trouble answering questions about geometric attributes. A lot of times they get the vocabulary mixed up--the can't remember which are the vertices and which are the edges. Another common mistake is that they leave out some when they count. And faces are the hardest to count, because it's really tough to mark them. So today I have some tips for helping kids count geometric attributes.
- Help kids develop a routine for counting vertices, edges, and faces. I typically count the attributes in the order shown below, because vertices are the easiest and faces are the hardest.
- Have students record their counts. I see kids try to hold the numbers in their heads, and that's often not successful.
- The V in vertex actually makes a vertex. A capital E is made up of a bunch of straight lines, and that's just like edges. The faces are the two-dimensional figures that make up the 3-dimensional shape.
- Vertices are marked with small circles and the edges are marked with a little dash. But teach kids to use an organized approach for counting. For example, to count the vertices below, the square on the bottom has 4 vertices--mark those first. Then mark the vertex on the top. Likewise, when marking edges, count the 4 on the square base first and then the 4 on the triangular faces.
- To count faces, I have the kids decompose the figure into its 2-dimensional figures. You can see below how it looks. I see 1 square and 4 triangles, so it's a total of 5 faces.
|Click on the picture to grab a free copy of this sheet for practice|