ABSTRACT
They begin by challenging students to form and compute the area of as many triangles as they 'can with a base of four on a 25-pin geoboard. Students count the geoboards square units, approximate some areas and keep track of their data to discover that triangles with areas of 2, 4, 6, or 8 can be formed. However, some students collaborate and place two geoboards together to find additional possibilities. Directing the students' attention to the base and height, the teachers ask students to try and connect the measures to areas of other figures they previously studied. The idea that the base and height form a rectangle that doubles the triangle's area becomes readily apparent as students examine the data. Not having any formalized rule, students proceed to test this conjecture to in other examples.
