Learning from a Slinky

If you've played with a Slinky for more than five minutes, you've probably mastered all the classic moves. But it turns out those humble coils have a surprise up their sleeves. Do this:

1) Dangle a Slinky above the ground as though you were holding a fish by the tip of its tail.
2) Let it extend to its full length.
3) Let go.

If you don't have a Slinky, do this:

1) Watch the first video.
2) Make a prediction.
3) Watch the second video.



Did you see it?  If not, try it again and this time keep your eye on the bottom of the Slinky.



Did you notice that as the top of the Slinky starts to fall, the bottom doesn't drop?  It just hangs in the air, levitating, as if it had its own magic carpet. It will stay there, hovering quietly, until a wave, or signal, passing through the Slinky finally reaches it. Apparently, the bottom doesn't know it's supposed to fall, so it sits there, seeming to defy gravity, until the very end.  (For a more detailed explanation check out http://www.wired.com/wiredscience/2011/09/modeling-a-falling-slinky/.)

This isn’t a magic trick.  It is a physics principle that can be proven by using words like equilibrium, gravity, and compression wave and by applying Hooke's law in conjunction with Newton's second law.  Plus lots of math.  The basic explanation is that the bottom coil will not twist and fall until it receives a signal the coil directly above it.  In other words, each coil doesn’t “know” it is supposed to fall until it is “told” by the coil above it.

This idea, that information has to pass through an object for the whole thing to know what to do, applies not just to Slinkys, but to ballpoint pens, arrows, baseball and, yes, even to learning.

I believe that too often children are rushed through the learning process.  That students are not given enough time to process information, or room to make mistakes, or even a moment to sit still and reflect.  Take math, for example.  Traditionally, math has been limited to algorithms and arithmetic, promoting such beliefs as speed and accuracy are more important than understanding; there is one right way to solve any problem; and math is mostly memorization.  My 7th grade math teacher, Mr. Sammons, certainly believed this. 

Mr. Sammons’ approach was simple: introduce an abstract concept such as multiplying fractions or dividing decimals by showing the class an efficient procedure, and never ever answer the question, “Why does this work?”.  I quickly learned that math didn’t have to make sense, it was nonsensical magic.  This jump from the top of the Slinky (mathematical concept) to the bottom (abstract generalization), skips all of the necessary connections in between.

Nearly thirty years of research has proven that skipping students to the abstract and rushing them through the learning process hinders students’ understanding.  Memorizing rules for moving symbols around on paper may be the filing of facts, but it is not the learning of mathematics; much like memorizing names and dates is not learning history.  Understanding a subject means getting inside it and seeing how things work, how things are related to each other, and why they work like the do.

Instead of focusing on algorithms and shortcuts, the teachers at Lipscomb Academy build understanding over a period of time; first through informal exploration moving to representational activities, using manipulatives, games and other tools.  This developmental method allows children to personally construct meaning and prepares them for the abstract.  For instance, in second grade, students are asked to solve multi-digit subtraction problems.  They might solve such problems by counting up from the smaller to the larger number, or by using tools such as a number grid.  Once a student has had successfully explored a variety of valid approaches, algorithms are introduced.  Allowing children to go through this process validates their intuitive methods and reinforces the fact that math makes sense and can be used to make sense of the world.  It can even explain why a Slinky seems to hover in mid air after being dropped.

Jonathan Sheahen
Elementary School Principal
Lipscomb Academy