Body Math

Over the next few weeks (and maybe longer), my math group will be applying what they know about measurement and learning about ratios as it applies to their bodies. 

We started on Monday we we attempted to figure out the ratio between our femur and our height. Using estimation skills and their hands, most children were pretty confident their were about 3.5 - 5 femurs to one body. I told them they were actually all very close - supposedly we have a 4:1 ratio - approximately 4 femurs to one body height. But how could we check to make sure?

We decided to measure our height and the length of our thigh bone and compare. Using the appropriate tool is important for accuracy. It soon became clear that yardsticks or rulers might be a little trickier to use than tape measures. We checked to make sure everyone used the same unit of measure - they chose inches, not centimeters.

Once they had their two numbers, I posed the question - now what? What can we do to one or both of these numbers to prove that four femurs is equal to the height of one person? Several children mentioned that we could add the femur length four times. One child added that we could "times" it. Both solutions could work, of course. Taking a random sample, we found at least one child with a perfect 4:1 ratio - June is 52 inches tall with a femur length of 13 inches.

On Tuesday we continued on with this type of lesson by watching a short PBS video called EcoHaven CSE, where a team of children detectives try to find who stole a giant cyberbeast using clues left by footprints. Using their knowledge about ratios, the team is hot on the trail. One of the clues was that feet size generally is associated with height - the bigger the foot, the taller the person. Another clue was that the size of your foot, measured from the tip of your big toe to the heel, is also the length of several other body parts. To the groans of the audience, we left the detectives in a rather precarious position in order to do some exploration of our own.

Using yarn to make their "foot measures," we tried to find 3 other places on our bodies that matched exactly - the forearm, wrapped around the fist, and from the crown of the head to the chin. And, just for fun, we read an old favorite, How Big is a Foot?

It has just begun, but is very clear there is a lot of fun to be had with measurement - with the bonus of learning some lovely bone and body part names!