Course Guide - USAID Teacher Education Project

Students will use an integer number line like the ones above not only toexperiment with addition and subtraction of integers in the next session,but also to explore several other topics today: opposites, absolute value,a four-quadrant coordinate plane, and the use of integers in real lifesituations.• Two-colour counters: This is a model that will be used in the next twosessions on operations with integers. If you have not worked with 2-colour counters, it is crucial that you practice with them beforeintroducing and using them in the next two sessions.Commercial two-colour counters usually have black or red on one sideand white or yellow on the other. However, two-colour counters can bemade by simply taking a bag of large white beans and marking one sidewith a crayon or felt tip marker. Detailed instructions on using 2-colourcounters to model addition and subtraction with integers are included inthe article above and in the “Integer Chips Teacher Script” documentthat will be used in the next two sessions.• Numerical patterns: Although not a hands-on way of working withintegers, number patterns are a way to stress that our number system isan orderly and logical one.4 –1 = 34 –2 = 24 –3 = 14 –4 = 04 –5 = ?4 –6 = ?• For each positive integer there is a negative integer that is called its “opposite.”For example, the opposite of 2 is -2; the opposite of -5 is 5. In a pair ofopposites, each number is equidistant from 0 on opposite sides of the numberline. More important, when two opposites are added their sum equals zero. Thisconcept of “zero-sum pairs” is the foundation of using two-colour counters tomodel integer addition and subtraction in the next session.