Triangles on the Geoboard
- Tibor Marcinek
Calculating the area of a triangle using the triangle area formula sounds like an easy task. Many students, however, will stumble when they try to identify a suitable base and the corresponding height. In this activity, you will see why (and when) it can be a problem. Link to the printable page is under the applet. 1. Draw all altitudes of the given triangles. 2. In each of the triangles, select the height that is easy to calculate. Find the corresponding base and apply the formula to find the area. 3. Reflect on the activity and explain possible stumble blocks for students and how to rectify them. You can use this worksheet to review the Geoboard method of finding areas (i.e. without using any formulas). 4. Find the area of the given triangles using the Geoboard method. 5. Check if your answer in 2. matches that in 4.