Think! Challenge: Scales

In week twenty of the Think! challenge, the kids were asked to:

Use some or all of the following materials to build a scale. Then see if you can balance it with 5 pennies on each side.

2 pencils
an eraser
a cup
4 straws
4 paperclips
2 pieces of paper
1 item of your choice
4 inches of string
4 inches of tape

You may use scissors in construction but not the solution.

Georgia chose an empty tissue box for the item of her choice. She cut it up to make two small rectangles for the pennies to sit on. She used the two pencils and a straw to make a tripod, and used some string, tape, and paperclips to make it stand. The crossbar was made from a straw, and she used strips of paper to hang the cardboard holders.

But when she tried putting the pennies on they wouldn't stay.

So she took off the cardboard rectangles and added rolled up paper and paperclips to hold them in place. She also used the eraser to stop the straw from sliding. Now the pennies would stay!

And that was her solution that we submitted to the Think! site. But she wasn't done with her scale. She decided to weigh some other items. She measured 1 tablespoon of flour and 1 tablespoon of granulated sugar into bags.

But when she went to weigh them the straw leg of the tripod bent.

After swapping the straw for another pencil, she weighed the bags and found that sugar weighed more than flour, even though they were the same amount. So we talked about density.

Georgia went on to weigh some of her horse figurines and other small toys. She loved this challenge.