Kid Science: How to Make Your Own Balance Scale

It’s not always easy for kids to see how objects relate to each other, especially regarding size and weight. That’s where a balance scale can come in handy. This simple, ancient device allows kids to see how the weight of objects relates to one other. You can make an easy balance scale at home with a coat hanger, some string and a couple of paper cups!

What Your Child Will Learn (or Practice)

• How to compare and contrast objects
• Estimation skills
• Measurement skills

Materials Needed

• A plastic hanger or a wooden hanger with notches. You'll want a hanger that won't allow the strings holding the objects to be weighed to slide off.
• String or yarn
• A single-hole punch
• Two identical paper cups (Try to avoid wax bottom cups, as they add uneven weight.)
• A pair of scissors
• Measuring tape
• Masking or packing tape

How to Make the Scale

1. Measure two pieces of string two feet long and cut.
2. Make holes to attach the string to the cups. Make a mark one inch below the rim on the outside of each cup. 
3. Have your child use the single-hole punch to make holes in each cup. Punch a hole on either side of the cup, along the 1-inch mark. 
4. Attach the hanger to the wall, using a cup hook, doorknob or a level bar for hanging clothes or towels.
5. Tie the string to each side of the cup and let it sit in the notch of the hanger. The string should support the cup like the handle of a bucket.
6. Repeat this process with the second cup.
7. Ask your child to steady the hanger to make sure the cups are hanging at the same level. If they are not; adjust the string until they are even.
8. When they look even: use a piece of tape to secure the string in the hanger’s notches.

Show your child how the scale works by putting a penny in each cup and then adding another coin to one of the cups. The scale will tip toward the cup with multiple coins in it.

Using the Balance Scale at Home

Once you’ve made your balance scale, it’s time for your child to try it out. Encourage her to take out some of her smaller toys and explore the scale. Once she gets the hang of it, you can help her compare the weight of different items and take about how to compare them.

Now teach him about units of measure. A penny can represent a standard unit of measurement, and we can use it to represent the weight of different things by a common name. For example, an alphabet block might weigh 25 pennies, but a pencil only weighs 3 pennies. Ask your child questions to help her draw conclusions, such as:

• Which cup has the heavier item in it?
• Why does one cup stay up while the other goes down?
• Do you think this would work if we put the hanger somewhere else? Why or why not?
• How many pennies do you think Toy A weighs? Is that more or less than Toy B?

This simple activity brings home a number of lessons. Making a scale teaches elementary physics as well as standardized measures, and affords you a great opportunity to learn along with your child.