Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table. For example, know that 1 ft is 12 times as long as 1 in. Express the length of a 4 ft snake as 48 in. Generate a conversion table for feet and inches listing the number pairs (1, 12), (2, 24), (3, 36), ...
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
A kilometer is 1,000 times as long as a meter, a pound is 16 times as heavy as an ounce, and an hour is 60 times as long as a minute. Fourth graders learn these relative sizes within each measurement system: metric length (km, m, cm), metric mass (kg, g), customary weight (lb, oz), liquid volume (l, ml) and time (hr, min, sec). Knowing that 1 foot is 12 times as long as 1 inch is a multiplicative comparison, so this standard links directly to 4.OA.A.1.
Using those relationships, students express a measurement given in a larger unit in terms of a smaller unit. A 4-foot snake is 4 × 12 = 48 inches long, and 3 kilograms is 3,000 grams. Students record the pattern in a two-column conversion table, such as feet and inches with the pairs (1, 12), (2, 24), (3, 36). Reading and extending these tables shows that every row grows by the same amount, which is the conversion factor.
Conversions in this standard always go from larger to smaller units, which means multiplying, so the numbers grow.
Converting 5 meters to centimeters as 5 ÷ 100 gives a tiny number. Remind students that smaller units mean more of them, so the number must grow.
Students used to metric units sometimes treat 1 hour as 100 minutes. Time conversions use 60, so a clock face is a useful reminder.
Some students think a gram is bigger than a kilogram. Handling a paper clip (about a gram) and a bag of flour (about a kilogram) fixes the sense of scale.
Make a conversion table for feet and inches up to 5 feet, then find the length of a 4-foot snake in inches.
Answer: The 4-foot snake is 48 inches long.
Pair each conversion with a physical benchmark: a meter stick, a 1-liter bottle, a 1-pound bag of beans. Students who have handled the units estimate better and catch impossible answers.
Tables are a favorite assessment format, often with a missing row or a request to extend the pattern. Practice filling tables both forward and from a middle value, such as finding the row for 7 hours.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: 500 (also accepted: 500 cm)
1 meter = 100 centimeters, so 5 meters = 5 × 100 = 500 centimeters.
Answer: 48 (also accepted: 48 oz, 48 ounces)
1 pound = 16 ounces, so 3 pounds = 3 × 16 = 48 ounces.
Answer: D) 120 minutes
1 hour = 60 minutes, so 2 hours = 2 × 60 = 120 minutes.
Answer: 4000 (also accepted: 4,000, 4000 g)
1 kilogram = 1,000 grams, so 4 kilograms = 4,000 grams.
Answer: B) (4, 12)
1 yard = 3 feet, so 4 yards = 4 × 3 = 12 feet. The next pair is (4, 12).
Answer: 420 (also accepted: 420 seconds)
1 minute = 60 seconds, so 7 minutes = 7 × 60 = 420 seconds.
A full lesson with slides, activities and an exit ticket on measurement units and conversion tables, pitched to grade 4 and editable in PowerPoint or Google Slides.
Make a lesson →A printable, differentiated worksheet on 4.MD.A.1 with an answer key, ready in about a minute.
Make a worksheet →Turn measurement units and conversion tables into a quiz students answer online that marks itself, with a class summary for you.
Build a test →km, m, cm; kg, g; lb, oz; l, ml; and hr, min, sec. Many classes also include feet, inches and yards, which appear in the standard's own example.
The focus is converting larger units into smaller ones. Converting in both directions, including with decimals, is part of fifth grade (5.MD.A.1).