Balance Scale

Little levels (ages 4 to 6)

1. Heavy or light? Elephant or feather, bear or balloon, rock or leaf: which side goes down?
2. Which has more? Compare apples on the two pans, including a tie.
3. Make it balance Add apples to the right pan until the beam is level.
4. Read the scale Say which side is heavier from the tilt of the beam.
5. Mystery box A box balances some apples; how much does it weigh?

Big levels (ages 7 to 9)

1. Missing number 7 = 3 + ?: add cubes to balance the scale.
2. Two on each side 4 + 5 = ? + 3: add up the left, then balance.
3. Weigh the toys Weigh a duck, a car and a bear in cubes, then order them.
4. True or false? Is 5 + 2 = 8? The scale checks each number sentence.
5. Doubles Make 10, 8 and 14 with two equal sides.
6. Solve for the box Box + 2 = 9, box + 5 = 11, box + box = 8.

The big ideas

• The heavy side goes down. A balance scale compares two things: whichever is heavier pulls its pan down. More of the same thing weighs more.

• Level means equal. When the beam is level, both sides weigh exactly the same. That is what the equals sign means: both sides are worth the same.

• Weigh things with a unit. Counting how many cubes balance a toy gives it a number. Then toys that look very different can be compared and ordered.

• An equation is a balanced scale. 7 = 3 + ? asks how much the right side needs to balance seven. True sentences balance; false ones tip.

• Find the unknown by taking away what you know. If a box and a two balance a nine, the box must be nine take away two. Two equal boxes balancing eight are four each.

Try it at home

1. Hanger scale Hang a clothes hanger on a doorknob and clip a bag to each end. Put things in the bags and see which side goes down.
2. Weigh in blocks Use your hanger scale to weigh small toys in building blocks or coins. Write each toy's number and order them.
3. Balance sums Put 4 and 5 blocks on one side and 9 on the other. Then try 4 and 5 against 8. What happens?
4. Guess the heavier Hold a shoe in one hand and a book in the other. Guess which is heavier, then check on the scale.

Ask after playing

• If a scale balances with 6 on one side, what must be on the other side?
• Why did the elephant side go down?
• Is 3 + 4 = 8 true or false? How would the scale show it?