Wednesday, October 1, 2014

Simple Machines Review the Apple Farmer Way

Wondering what to do with all your apples from a visit to the local apple farm in the fall?  How about some apple math and a composite simple machine activity?

We have had a lot of fun learning about some of the simple machines:  pulleys, ramps and wheels.  So today we decided to explore how we can put these together to do a more complex task.  We setup a little apple farmer tractor and trailer on a trail.  The tractor is powered by a bag that could hold weights attached to the front axle along a path (piece of a cardboard box).  A pulley was attached to help change the direction of the string over the edge of the table.   So we have wheels on our tractor, a pulley redirecting the string and a potential ramp.

We needed to add weights to the bag to pull the tractor forward.  Seeing though this was a little heavy we decided to use apple slices as our weights.  This was also a great way to talk about fractions.  We started talking about how one apple did not give us very many options when it came to adding different numbers of weights and how cutting it up could give us more pieces.

So first mommy cut it in half or two pieces.  Mommy then cut each of those in half to get quarters or four pieces.  Finally mommy cut the quarters in half to get eights.  We played around with the slices talking about how different combinations gave different fractional values.

Now we were ready to start.  How many apple slices did we need to add to make the tractor move.  1... 2... 3!

Three apple slices were the same weight as the tractor and our tractor moved forward a bit.  Now how many slices would we need if we lifted the ramp?  1... 2... 3... 4... 5!

We removed all the slices and made the ramp higher.  So would we need more or less slices to move our tractor?  1... 2... 3... 4... 5... 6... 7!

What was great to see was that the girls had a strong intuition that it was harder to go uphill and could guess that you would need more apple slices to pull the tractor up the steeper hill.  Even though they knew this they were still excited when it the tractor moved!

But what will happen when we change the weight of our tractor?  Or in the case of our story - the farmer was now harvesting his crops and needed to bring his apples home.  First we put the apple on the trailer and moved the tractor around and the apple fell off.  So we decided to make sure our apple was secure we should tape it to the trailer.   Bug suggested that this might need more slices to move the tractor up the ramp as the trailer was heavier.

So we put in the same number of slices as before and it did not move.  So what would happen if we added another apple of almost equal size to the bag?

Whoo hoo!  It moved!  Our tractor was able to pull the apple up the ramp!

We had a lot of fun with this activity using our different simple machine together to help our apple farmer!



  • 3 apples
  • toy tractor and trailer
  • string
  • pulley
  • piece of cardboard
  • ziploc bag
  • books
  • tape


  1. Make a small hole in the corner of the ziploc bag and tie the string.
  2. Tape the pulley to the bottom of the cardboard.  Tape the other end of the cardboard to the table so that the pulley end extends over the edge.
  3. Thread the string from the bag over the pulley and tie onto the tractor.  
  4. Move the tractor to the start of the cardboard so that the bag is off the ground.
  5. Cut an apple into eighths.
  6. Put one piece of apple at a time into the ziploc bag and watch to see if the tractor moves forward.
  7. When the tractor moves forward, stop and count the pieces as you take them out of the bag.
  8. Raise one side of the ramp with a book and repeat steps 6 and 7.  Note if more or less apple slices were used.
  9. Raise the ramp even higher and repeat steps 6 and 7.
  10. Tape an apple to the tractor or trailer and repeat adding apple slices. The tractor should not move so add the additional apple and see what happens!


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