Puzzled Penguin has been struggling with adding 2 digit numbers to 2 digit numbers. He has learned to regroup but often times he is not sure what that means or when to do it. Students looked at a variety of problems Puzzled Penguin completed and talked with partners to brainstorm what misconception Puzzled Penguin had about regrouping. A few students shared their thinking with the class and taught Puzzled Penguin that adding a group of 10 above or a group of 10 below is only necessary if the sum of the ones is greater than 9.
