Each one of these problems can be used for a 45 - 60 minute lesson. These problems have a variety of joining, separating, comparing, multiplication and division problems with unknowns in various positions. You may change the number sets based upon the needs of your students. Providing at least 2 number choices provides built- in differentiation.
First, the teacher and students unpack each CGI problem together and then children can work independently or in groups on a strategy.
Teachers may ask students to show two different strategies for each problem and then move onto the challenge problem.
In the middle of the lesson a teacher may ask a student or group of students to share out. At the end of the CGI lesson a teacher should purposefully highlight student strategies. Students can compare and contrast different strategies or explain their reasoning. Discussing incorrect and correct strategies helps students find their own errors and become more efficient mathematicians by learning a variety of strategies or ways to think about a problem.