Same Science › Working with data › Metric units and conversions
How do kids convert metric units?
Science uses metric units: meters for length, grams for mass, liters for volume. Every unit is 10 times the next one, so converting is just moving the decimal point. Kids use the staircase King Henry Died By Drinking Chocolate Milk (kilo, hecto, deka, base, deci, centi, milli): going down a step multiplies by 10, going up divides by 10. 2.5 m down two steps to centimeters is 250 cm.
- Base units: meter, gram, liter.
- Going down (to smaller units): multiply by 10 per step.
- Going up (to bigger units): divide by 10 per step.
Why schools teach it
The units every lab uses
Fourth and fifth graders convert measurements within one system (4.MD.A.1 and 5.MD.A.1), and science labs record everything in metric. Using mathematics in science is NGSS science practice 5.
Because every step is 10, there's nothing to memorize except the order of the prefixes. The staircase picture makes the direction obvious.
At the kitchen table
What to say, and what to skip
Say this
Is the new unit bigger or smaller?
Smaller units mean a bigger number.How many steps apart are they?
Which way does the decimal move?
Down the stairs: right. Up: left.Does the answer make sense?
1 km is long, so it's a lot of meters.
Skip this
- Converting through feet and inches.Stay in metric; it's all tens.
- Mixing up mass and weight units.Grams measure mass in metric.
- Moving the decimal the wrong way.Ask: should the number get bigger or smaller?
See it in action
Converting 3,400 mL to liters
milli to base: up 3 steps
divide by 10 three timesMove the decimal 3 places left
3400. → 3.400Answer
3.4 L
Hecto and deka are rarely used, but they keep the steps counted correctly.
Free practice sheet
Make a metric conversion sheet
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Parents also ask
What does King Henry stand for?
Kilo, Hecto, Deka, (base unit), Deci, Centi, Milli. Some versions say “King Henry Died Unexpectedly Drinking Chocolate Milk,” with U for unit.
What are the most common conversions?
km and m, m and cm, cm and mm, kg and g, L and mL.
Why don't scientists use feet and pounds?
Metric is used worldwide in science, and converting is just moving a decimal.
Is a mL the same as a cubic centimeter?
Yes, 1 mL = 1 cm³. That comes up in middle school density labs.