Course Guide - USAID Teacher Education Project

• Compasses• Assorted cylinders and boxes (Have students bring these to class.)Read through the plans for this week's three sessionsWeeklong Overview:Session 1 begins by using string to surround various cylinders and by comparing thelength of the string to the cylinder's diameter. By charting the results, students shouldcome to the conclusion that there is a relationship between the diameter and theperimeter of the cylinder (which is called circumference). They may express thisrelationship as "three and a little bit more," which will help them understand pi.During Session 2, students will extend what they learned about pi to find theapproximate area of circles.Just as they explored circumference prior to using a formula, students will explore thearea of circles by using a counting method and a novel visualization (radius squares)to make sense of the formula A = pi * r 2Session 3, the last for this week, builds on what students know about area of bothrectangles and circles to introduce the concept of surface area.Up to now the emphasis has been on the measurement of 2-dimensional planefigures. Surface area, however, relates to the multiple areas that cover a 3-dimensional object.This means that for cuboids students need to consider not only length and width, butalso height. For cylinders they will be dealing with a rectangular piece (like the paperlabel on a can) as well as a circular top and bottom.