Measure and estimate liquid volumes and masses of objects using standard units of grams (g), kilograms (kg), and liters (l). Add, subtract, multiply, or divide to solve one-step word problems involving masses or volumes that are given in the same units, e.g., by using drawings (such as a beaker with a measurement scale) to represent the problem.
Official wording from the Common Core State Standards for Mathematics (© 2010 National Governors Association Center for Best Practices and Council of Chief State School Officers). View on thecorestandards.org
How heavy is an apple? How much water fits in a bucket? Third graders answer questions like these with metric units: grams and kilograms for mass, and liters for liquid volume. Building benchmarks is the first step. A paper clip has a mass of about 1 gram, a large textbook or a liter bottle of water is about 1 kilogram, and a liter is the amount in a large water bottle. With these anchors, students make sensible estimates and catch silly ones.
Students then measure with real tools, reading scales and graduated beakers, and solve one-step word problems with all four operations, such as finding the total mass of 4 bags of flour that are 2 kilograms each, or how much juice is left after pouring 3 liters from a 10-liter cooler. All quantities in a problem use the same unit, so no conversions are needed in grade 3. Drawings of beakers and scales help students see the situation, and reading a scale with intervals of 2, 5 or 10 links this work to number lines and skip counting.
Students often assume a large object has a large mass. Compare a big balloon and a small rock on a balance to break the link between size and mass.
On a beaker marked every 2 liters, children may count each line as 1. Ask what each space is worth before reading.
A child may say a pencil weighs 5 kilograms. Benchmarks (a paper clip is about a gram, a liter of water is about a kilogram) help students judge.
A tall narrow glass can look fuller than a wide bowl holding more. Pour between containers to compare volumes directly.
A cooler holds 18 liters of water. The water is poured equally into 3 jugs. How many liters are in each jug?
Answer: Each jug holds 6 liters.
Set up measuring stations with balance scales, kitchen scales, gram cubes and liter containers. Let students estimate first, record, then measure and compare. Reading a scale is a number line skill, so practise with scales that go up by 2, 5 and 10.
Test questions often show a beaker or scale and ask for the reading, ask which unit is reasonable, or give a short word problem. Keep problems to a single step and a single unit, as the standard does.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: D) about a gram
A paper clip is very light, about one gram. Liters measure liquid volume, not mass.
Answer: 20 (also accepted: 20 kilograms, 20 kg)
4 equal groups of 5 kilograms: 4 × 5 = 20 kilograms.
Answer: 23 (also accepted: 23 liters, 23 l)
35 - 12 = 23 liters remain.
Answer: C) liters
Liters measure liquid volume, such as how much water a container holds.
Answer: 25 (also accepted: 25 liters)
Halfway between 20 and 30 liters is 25 liters.
Answer: 400 (also accepted: 400 grams, 400 g)
150 + 120 + 130 = 400 grams.
Measure the length of an object by selecting and using appropriate tools such as rulers, yardsticks, meter sticks, and measuring tapes.
Estimate lengths using units of inches, feet, centimeters, and meters.
A full lesson with slides, activities and an exit ticket on measuring liquid volume and mass, pitched to grade 3 and editable in PowerPoint or Google Slides.
Make a lesson →A printable, differentiated worksheet on 3.MD.A.2 with an answer key, ready in about a minute.
Make a worksheet →Turn measuring liquid volume and mass into a quiz students answer online that marks itself, with a class summary for you.
Build a test →No. In grade 3 all quantities in a problem use the same unit. Converting between units comes in 4.MD.A.1.
About 1 gram for a paper clip, about 1 kilogram for a liter of water or a dictionary, and 1 liter for a large water bottle are helpful anchors.