How to Teach Metric Conversions So Kids Get It

Wondering how to teach metric conversions? If you want kids to get it, scaffold from simplest to most complex. In fourth or fifth grade, begin with easy whole number conversions. Support understanding with conversion charts. Then scale instruction to include decimals.

Mr. Grow Learns How to Teach Metric Conversions

Our favorite fourth grade teacher sat at the side table with her student teacher. “Let’s talk about how to teach metric conversions in fourth and fifth grades,” she said.

“Shouldn’t it be different for each of those grades?” Mr. Grow asked.

“Not necessarily,” Ms. Sneed replied. “By the second semester, fourth graders have rudimentary understanding of decimals. Therefore, they’re ready for the same sequence as fifth graders.”

She pointed to the measurement unit displayed her laptop. “The key,” she said, “is scaffolding. That way, they grow bit by bit and aren’t overwhelmed.”

Introduce the Unit with a Centimeter Cube

As she continued, Ms. Sneed picked up a small, blue centimeter cube. “Whenever I teach metric conversions to my fourth grade math class, I begin with this little guy.”

Mr. Grow looked slightly confused, but listened carefully.

“This represents one cubic centimeter, also known as cc or centimeter cubed. Each side is one centimeter in length.

“If this was made of water, it would have a volume of one millimeter. Furthermore, one cubic centimeter of water has a mass of one gram.”

Mr. Grow’s eyes widened. “Really? I never knew that.”

“Yep. Discussing this also helps kids build spatial concepts related to metric measures. And, did you know, that a centimeter is about the size of the width of your little finger?”

Mr. Grow held his pinky to the block. “Why yes, it is!”

Before you teach metric conversions, show kids the relationships between units using a centimeter cube.

Provide a Cheat Sheet for Guidance

Ms. Sneed scrolled to the next page of the unit. “The next thing in your how-to-teach-metric-conversions journey is this little cheat sheet. More than anything, it helps kids with vocabulary and abbreviations. You can distribute and discuss it on the first day of instruction.”

Use this cheat sheet to teach units of metric measurement.

Begin with Millimeters and Centimeters

“As I said before,” Ms. Sneed continued, “it’s important to scaffold. You’ll begin to teach metric conversions with millimeters and centimeters. Some people think it’s because it’s the smallest unit of length, but no. Actually, we begin with these units because kids only have to multiply and divide by ten. It’s easy.”

Whole Numbers

Once again, she scrolled down. “On the first page, kids complete a conversion table. Right away, kids will notice that they simply count by tens. Then they use the chart to complete the problems.”

Ms.Sneed pointed to the first five problems in the left-hand column. “Here, they can find answers on the table.”

Next, she motioned to the first five problems in the right-hand column. “Same on this side, but as you can see, it’s the inverse. They’re converting millimeters to centimeters.”

“I notice that the last five problems in both columns aren’t on the table,” Mr. Grow commented. “How will they solve those? Multiplication?”

A small smile slid across the mentor’s face. “I suppose they could, but that would be a challenge. Many students will notice that they can use partial products, but you may need to show others.”

Mr. Grow’s face went blank. “What?”

“Let’s look at this first problem: 15 cm = ____ mm. Kids know that 10 + 5 = 15. On the table, they find that 10 cm = 100 mm and 5 cm = 50 mm. They just add. 150. Easy.”

Now the student teacher shook his head. “This is not how I learned it. This is easier. So much easier.”

Ms. Sneed’s smile widened. “Not only that. These methods encourage kids to conceptualize mathematics much better than the rote ways we learned.”

Wondering how to teach metric conversions? Begin with the simplest concept: converting millimeters to centimeters. All kids need to do is multiply or divide by ten.


“On the next set of pages,” Ms. Sneed said, “we’ll introduce simple decimal problems. Since kids this age are just beginning to understand tenths and hundredths, the metric conversion charts are even more important. This worksheet is set up in the same way as the previous one. Kids can use the table to find the first five answers in each column. For the second set, they use partial products. Word problems round out the practice set.”

Mr. Grow studied the pages carefully. “I can see how this exercise would be great for students who are just learning about decimals.”

“Yes. As a matter of fact, when some teachers ponder how to teach metric conversions, they decide it should be kids first experience with decimals. You can use activities like this to teach decimals – or to reinforce them.”

When you think about how to teach metric conversions, introduce decimals with only millimeters and centimeters.

How to Teach Metric Conversions with Tables (You Should Do This!)

As Ms. Sneed continued, she scrolled through several pages of tables. “Using metric conversion charts for these early activities powerfully builds kids’ understanding of math.”

Conversion Charts

“For a long time, these charts didn’t fit in with my ideas on how to teach metric conversions. After all, I learned to convert through computing. I felt that the charts were a crutch. But my views changed.”

“How?” asked Mr. Grow.

Ms. Sneed blushed. “I tried it myself. As I filled in the columns, I noticed patterns, then relationships between various sets of units. Furthermore, I began to understand how the tables would help kids conceptualize whole number and decimal computation.”

“I see,” her mentee responded. “A crutch with benefits.”


When considering how to teach metric conversions, always include charts like this. Kids need the support when they're first learning.

Support Charts

Ms. Sneed scrolled to another set of tables. “As kids establish patterns, they can also benefit from metric conversion support charts. Here, they write the number from a math problem in the correct column. Then they use the pattern to figure the answer.”

“So,” said Mr. Grow, “if a problem asks how many centimeters in 40 millimeters, I would write 40 in the column under millimeters.”


“Then I would easily see that the answer was 4. Just divide by ten.”

“Or get rid of one zero, or move the decimal point one place to the left. For this, we place no judgment on which thought process kids should use.”

Math teachers can use tables like this to support kids when converting. As they work their problems, patterns help them.

Continue to Teach Metric Conversions of Length

“Armed with these tools (which is probably a better word than crutches),” Ms. Sneed said, “students can tackle more difficult and varied problems.”

Whole Numbers

Scrolling through the next few pages, she discussed three more worksheets involving metric conversions of length. “As you can see, each of these problem sets has three parts. At the top, they convert larger units to smaller units. In the middle, smaller to larger. And at the end, they solve word problems.”

“Wait,” said Mr. Grow. “The answers at the top will actually be bigger, not smaller.”

“Ah, you feel for it. This really trips kids up. Larger units contain a greater number of smaller units. So, for example, three centimeters equals 30 millimeters. To help students, discuss this often – and draw lots of pictures. For example, you could draw a line broken into three parts. In each of those parts, you’d mark ten units. That would help a child see that three larger units holds 30 smaller units.”

After kids know how to convert both whole and decimal units, provide mixed practice.


Next, Ms. Sneed scrolled to some decimal pages. “Our students will work with decimals in the same manner. However, you’ll notice that we do not mix whole numbers and decimals on the same worksheet. In order to scaffold, we keep them separate (and easier) at first.”

After kids know how to convert, provide mixed practice with decimals.

Now Teach Metric Conversions of Volume

“However, when we get to volume, we do put whole numbers on the same page. You’ll notice, though, that they’re in different sections of the worksheet. And again, metric conversion and practice charts are allowed.”

When thinking about how to teach metric conversions, remember to include volume. For kids in fourth and fifth grades, you should limit it to milliliters and liters.

Finally, Teach Metric Conversions of Mass

“The last section of metric conversions is mass. As you can see, the worksheet is similar to what they did for volume.”

Include mass - grams and kilograms - in your unit.

Finish Up with a Test

Mr. Grow sat back with a sigh. “I’m beginning to understand how to teach metric conversions. Additionally, I see how you scaffold instruction. Just like you said, moving bit by bit.”

Ms. Sneed nodded. “And at the end, as usual, we administer a test.”

“Can kids use conversion charts?”

Ms. Sneed sighed. “That’s a tricky question. I’m going to say yes, at least for fourth graders. But it really depends on the group that you’re teaching.”

Culminate your unit with a test.

Enjoy Teaching

Now Ms. Sneed sat back in her chair. “Figuring out how to teach metric conversions is tricky. But it’s much easier than customary measurement. After all, with metric, you’re just multiplying and dividing by multiples of ten. Tomorrow, we’ll talk about standard units of measurement.”

Now Mr. Grow sighed. “Okay. All of this is tricky. But now that I understand how to scaffold, I’m sure I’ll enjoy teaching it much more.”

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