Bubble Diameters From Janet Kindred, a third grade teacher at Moore Elementary School in Griffin, Georgia: "I give my students small cups of bubble solution to spread on their desks. Students must dip their straw into the cup before carefully blowing a bubble onto the desktop. When the bubble pops, they get a perfectly round circle of which the diameter can be measured. The students find four or five diameters and then I let them play with the rest of the solution. After cleanup is complete, we take the diameter measurements and find their average. I use this time to explain how teachers average grades and demonstrate how much even one missing or low grade hurts a grade point average. I've used this activity when working on measurement but it's also a fun end of the year review activity."