Thursday, September 11, 2014

Wheels: The Center of a Ball

When kids are young, it is hard for them to differentiate between something round (a sphere) and a circle.  To them, they are both round.  Comparing a wheel and a ball, kids may also thnk they are both round.  A wheel is round, but it is not spherical in shape.  It is circular.  To find out how easy it is to use the simple machine wheel and axle, we examined how a wheel is part of a sphere.   We then wanted to explore which would be easier to use- a ball or a wheel.  To demonstrate, Jelly Bean and Jumping Bean challenged each other in a ball rolling race- this was not easy.


The ball was definitely hard to control.  It was not easy to roll it in a straight line- the girls were running after it everywhere as they tried to roll it around the chair!  So we looked at how we could change a sphere into another shape to see if it would be easier.


I cut the sides off the styrofoam balls we were using for our race to show Jelly Bean and Jumping Bean that a circle is the center of a ball.  This circle looked a lot like a wheel.


After some questioning on how we can roll the wheels, putting an axle on was suggested.


An axle on one wheel just did not work.  Oops, it tipped right over!


After brainstorming and thinking about wheels we see everyday, Jelly Bean and Jumping Bean came up with the conclusion that there needs to be two wheels on the axle.  Rolling the two wheels on an axle was much easier to control, and it went in a straight line.  Yay, success!

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Supplies:
  • 2 styrofoam balls found at craft stores (ours were 5 inches in diameter)
  • pencil or stick for axle
  • serrated knife for parents to cut off the sides

Instructions:
  1. Child will roll the styrofoam ball from a start point to an end point to see that the ball does not roll in a straight line.  We made a game out of it and raced around a chair back to the starting point.
  2. Parent will cut off each side of two styrofoam balls leaving the center of each as the wheel.
  3. Poke the pencil through the center of the wheel acting as the axle.
  4. Roll the single wheel and axle and discuss why the wheel does not move far.
  5. Place another wheel on the opposite side of the axle.
  6. Roll the wheel and axle again and discuss that with two wheels, it moves easier and in a straight line.
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