Travel on Sand (or Snow)

My son asked me for money to buy a book at the school book fair.  I assumed he would purchase a Star Wars or Superhero type book.  I was correct.  BUT, it was a Star Wars Science Fair Book so I was pretty impressed at his choice.  We are slowly trying out some of the classic experiments in the book with a Star Wars twist but seriously they can be done without the Star Wars connection.

This particular investigation explores how to travel in the desert/snowy environments of the planets that the Star Wars characters live on.  We added some of our own extensions to this as well.  Super easy to get this set up!

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Here’s what you need to get started:

  • box or container (we use the plastic shoeboxes from the dollar store)
  • enough sand to fill the container about 1/2 full
  • cardboard (we used leftover cardboard from our multiple Amazon deliveries)
  • scissors
  • jar lid
  • dime or penny
  • pencil

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Before starting this activity, I asked my son how it feels to walk on the sand at the beach.  Is it hard to walk?  What happens to your feet as you step in the sand?  I then had him take the pencil and press gently into the box of sand and obviously, the pencil immediately sank in.

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Next we used the jar lid and coin to draw 2 circles of different sizes.

IMG_2665I helped him cut the circles out of the cardboard since it was so thick and difficult for him to do on his own.

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Next, he placed the small cardboard circle on the sand and used the pencil eraser to apply some pressure as before.  We repeated with the larger circle.

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The smaller circle did eventually begin to sink into sand but not like the pencil did.  The large circle did not sink at all.  I asked my son why he thought that was.  I asked him if it hurts more to poke him with a sharp pencil or with my flat palm.  I asked him some probing questions and then it led us to talking about skis and snowboards and why they don’t sink in the snow.  So guess what?  We cut out skis and snowboards out of the cardboard to test out his theory.

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The snowboard did pretty well under pressure.
IMG_2675The skis buckled a bit (more due to the cardboard bending than the shape/surface area) but still didn’t sink.

We tried out snowshoe shapes as well (my son thought they looked more like tennis rackets…sigh).  Those held up pretty well, too.

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This simple experiment was really so easy but led to some fantastic discussion and experimentation with my son and I.  I thought it was going to take us 5 minutes but by the time we tested all our shapes and discussed his theories and the science behind it all, it was 45 minutes!  Wow!  Time flies when learning is FUN!

And lastly, the Lego Star Wars Minifigures went into the box for some playtime:)

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The Science behind the activity:

In physics, students are taught that a force applied over a given area results in pressure or P=F/A.  The greater the force applied, the greater the pressure.  BUT, if you increase the area over which the force is applied, you can REDUCE the pressure.  This is why it hurts more when someone steps on you with the tip of a high heel versus a flat shoe.  Or why it hurts more if your little brother pokes you with a toy sword versus a toy shield (I am not promoting violence but I do live with three little boys…)  It’s why you don’t sink in the snow with skis or on a snowboard but leave deep shoe prints while walking with just your boots.  It depends on how your body weight is being distributed over a small or large area.

Extension: Have your child make large cardboard or wooden versions of these that they can put on their feet and test it on in a sandbox.  Do you get the same results?

For more details and to see where I got this idea from check out this fantastic book we got from the book fair Star Wars Science Fair Book by Samantha Margles and sold by Scholastic Books.

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