Here’s a fun fall math activity for kids! Build a simple PVC pipe balance that will allow kids to investigate the weight of a pumpkin. And really, there is nothing inherently “fall” about the balance, so if you build one you can use it all year long.

We built a simple PVC pipe frame for our balance, but you could also create a balance by simply hanging the coat hanger over a door knob. The frame definitely has some advantages, and you can take it apart for storage. It’s more stable than someone opening the door while you’re using the balance – something that happens in our busy house! Also, kids can work wherever you’d like them to and not just in a doorway.

We chose coins and small rocks as our units for comparing weights. I set up this basic chart for Owen (2nd grade) to fill in. He also added math sentences with his own explorations.

I asked Owen to guess how many rocks would be equal to one pumpkin. He guessed that it would be 4. We were both surprised at how many rocks it took!

It took 13 rocks to equal the weight of one pumpkin.

And it took 60 coins to equal one pumpkin!

Owen compared the weight of a small pumpkin vs. one of the larger ones. They were all small pumpkins, but there was some variation in size. The smallest pumpkin was equal to 60 coins, and the largest one was equal to 79 coins.

You can see that Jonathan added “Finn” to the chart – they had to find out how much his Star Wars Finn action figure weighed!

How to make the PVC pipe balance:

We didn’t buy anything for this project, believe it or not. We just keep recycling our PVC projects over and over, with the exception of the sand and water table which we won’t be taking down!

We used 3/4 inch PVC pipe.

You will need:

• 6 – 90 degree elbow joints (for the top and two bottom pieces)
• 2 – T joins
• 3 – 18.5 inch sections (for the vertical pieces)
• 2 – 20.5 inch sections
• 2 – 6.25 inch sections
• 2 – 1.5 inch sections
• 2 plastic containers
• string
• a hanger – ours is from IKEA
• 1 screw – ours is 2.25 inches long
• 2 – nuts
• a drill

The measurements don’t need to be exactly the same as what we used as long as the corresponding pieces are equal to each other. The overall dimensions of our balance assembled are 21 inches by 12 inches by 22.5 inches tall.

The baskets are corn starch containers that we cut the top off of.

Here is a close-up of the screw. We used a drill to make a hole in the PVC pipe.

It takes a little bit of adjusting to get the baskets to hang at the same height, but after that you’re done! The frame can easily be taken apart for storage.

We could fit two small pumpkins in our baskets, but I bet it wouldn’t be difficult to find larger containers to use with larger pumpkins.

1. ##### Kathy Sep 30, 2016

I absolutely love this idea! Thank you so much for sharing. I just asked my husband if he would build one. Yes! I know my 12 yr. old will love using this.