## Venn Diagrams for Small People

With the Holidays quickly approaching, we naturally think more about family and those we love.  In Pre-K this means many conversations pertaining to family members suffuse the day.  We take the opportunity each fall to direct this curiosity into a classifying challenge.  The set up starts like this:

We have two unidentified circles laying in  the middle of the room, surrounded by dolls.  The number of dolls is determined by the number of students in the class.  We make sure that each child has an array to pick from to represent his or herself.  After choosing a representative doll, the children must decide where their doll fits in our now labeled “brother” and “sister” circles.

Someone always discovers that we have two conundrums.  Where do you put your doll if you don’t have any brothers or sisters? What do you do if you have both?  Here we have a problem to be solved.

This year, a few children suggested that we should make a third circle to represent those with both brothers and sisters.  While we discussed the advantages and disadvantages to that solution, another child suggested we could just put them in both circles.  Of course our response was, “How?”

Following some childrens’ advice about yarn placement, we quickly adjusted the circles so that they overlapped.  (Note: All I’m doing in this photograph is moving the string.)  Once the overlap was established, it was easy to see how those with both brothers and sisters might be represented.

## Family Diagrams

In the past few weeks, the students have become quite interested in families and how they can be quite different. As a part of our morning meeting, we decided to investigate how many students had brothers, how many had sisters, and how many were only children. On the floor, we place a red circle and asked the student to place their doll inside the circle if they had a sister. If the students did not have a sister, they were asked to place their doll outside of the circle. We then replaced the red circle with a yellow one and repeated this same instructions for students with brothers.

Then we decided to put out both circles at the same time. One student raised her hand and noted that she has a brother and a sister. After some problem solving, the student suggested overlapping the two circles. She then concluded that students with both a brother and a sister could place their doll in the middle where the circles overlap. Without even noticing, the students had created a Venn diagram!

Now that the students had become familiar with grouping in this manner, we had them complete another Venn diagram for the morning message. This diagram involved the students deciding if they had a dog, a cat, both, or none of the above.