Your role during this time will be that of a facilitator. When students have completed their worksheets invite them to discuss what is represented in their graphs, difficulties they encountered producing the graphs and conclusions that can be made using these graphs. As with most lessons there are a number of ways you can evaluate the students' comprehension. Unable to identify numerator and denominator. No calculations are made.
Assistance is necessary.
Able to identify the numerator and denominator and calculations are attempted. Assistance is necessary. Able to add fractions with simple denominators. Calculations are made with few errors. Works independently sometimes needs assistance.