A girl pours lemonade from a big jug at her stand

Measurement Word Problems

Maya runs a lemonade stand. Her jug holds 2 liters. She just poured out 750 milliliters. How much lemonade is left?

4th Grade Math

Step 1: Make the Units Match

          The jug holds 2 liters. Maya poured out 750 milliliters.
          We cannot subtract yet because the units do not match!
        

Remember: 1 liter = 1,000 milliliters. So 2 liters = how many milliliters?

1 liter = 1,000 mL, so 2 liters = 2 x 1,000 = 2,000 mL. Always convert to the smaller unit first.

Step 2: Subtract

Now both amounts use milliliters. The jug had 2,000 mL. Maya poured out 750 mL.

2,000 - 750 = ?

2,000 - 750 = 1,250 mL. Think: 2,000 - 700 = 1,300, then 1,300 - 50 = 1,250. Maya has 1,250 mL left.

Let's Remember

          Solving Measurement Word Problems
        
          Step 1: Analyze the problem and convert to matching units.

          Step 2: Determine the operation: +, -, x, or divide.

          Step 3: Solve, then label your answer with its unit.

This plan works for distance, time, volume, mass, and money problems.

Read the Measurement Scale

0

250

500

750

1000

1250

1500

1750

2000

Maya draws her jug as a number line diagram in mL. To interpret the scale, look at two marks that sit next to each other.

From 0 to 250 is one jump, so each jump is 250 mL. Her answer, 1,250 mL, lands exactly on the fifth mark.

Watch Out!

          A Common Mistake
        
          Some students write 2 - 750 and get confused. Why is that wrong?
          The 2 counts liters, but the 750 counts milliliters.

Maya says: Mixing units is like subtracting 750 pennies from 2 dollars without converting. Convert first, then compute!

Practice: Time

Soccer practice starts at 3:45. It lasts 1 hour 30 minutes. What time does practice end?

3:45 + 1 hour = 4:45. Then 4:45 + 15 minutes = 5:00, and 15 more minutes = 5:15.

Practice: Money

Leo buys a notebook for $3.75 and a pen for $1.50. He pays with $10. Line up each decimal point before you compute. How much change does he get?

First add: $3.75 + $1.50 = $5.25. Then subtract: $10.00 - $5.25 = $4.75. Two steps!

Practice: Distance

A trail is 3 kilometers long. Ana runs the shaded fraction of the trail: 1/2. How many meters does she run?

Convert first: 3 km = 3,000 m. Then take half: 3,000 divided by 2 = 1,500 meters.

Practice: Mass

A vet weighs a dog. Its mass is 6 kilograms. The chart at the clinic uses grams. Fill in the blank.

6 kg = ? g

1 kg = 1,000 g, so 6 kg = 6 x 1,000 = 6,000 grams. Multiply to go from a larger unit to a smaller unit.

Practice: Minutes

A movie lasts 2 hours 15 minutes. Theo's timer only counts minutes. How many minutes should he set?

1 hour = 60 minutes, so 2 hours = 120 minutes. Then 120 + 15 = 135 minutes. Never just glue the digits together!

Challenge!

Sam's bottle holds 1.5 liters of water. He drinks 300 mL in the morning and 450 mL at lunch. How many milliliters are left?

Convert: 1.5 L = 1,500 mL. Add what he drank: 300 + 450 = 750 mL. Subtract: 1,500 - 750 = 750 mL left.

Think about your day. When did you last measure time, money, or distance? How could converting units have helped you?

Great Work!

0/9

correct

analyze determine interpret decimal fraction