Making change

What this lesson shows

$20 minus two prices, by counting up.

The worked example

The lesson works this one step by step: $20 − $7.45 − $3.80. Then your kid tries one like it on paper.

The steps

1. Add the prices
2. Count up to a whole dollar
3. Count up to 20
4. Add the jumps

Helping at home

Add the two prices first, dollars and then cents. Then count up from the total like a cashier: cents to the next whole dollar, then dollars to 20. Add the jumps for the change, and check by adding the change back to the total.

If your kid gets stuck

Add the two prices first.

Standards

• Common Core 4.MD.A.2
  Use the four operations to solve word problems involving distances, intervals of time, liquid volumes, masses of objects, and money, including problems involving simple fractions or decimals, and problems that require expressing measurements given in a larger unit in terms of a smaller unit. Represent measurement quantities using diagrams such as number line diagrams that feature a measurement scale.

More in this unit

• Tenths and hundredths
• Fractions as decimals
• 0.6 is not 0.06
• Comparing decimals
• A longer decimal isn’t bigger
• Adding tenths and hundredths
• One tenth more, one hundredth less
• Adding and subtracting decimals
• Line up the decimal points
• Fixed and variable expenses
• Profit
• Where to keep your savings