Can a blue shape be green? Can a round shape be yellow? For young learners, sorting objects based on their attributes can get a little confusing. In this fun math activity, first graders create a Venn diagram out of yarn and then sort cards into different categories based on their attributes. The challenging bit is deciding when a card needs to go into both circles! Sorting and classifying objects is an important skill that will make algebra easier for kids when they get to it.