Reveal Math Grade 4, Unit 9: Decimals
In this unit, your child connects fractions to decimals, writing tenths and hundredths both ways, adding tenths to hundredths, and comparing decimals like 0.4 and 0.38. Money and grids make the amounts concrete. It extends the fraction work from the units before it and leads into a unit on geometry.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 9?
- Renaming tenths as hundredths, so 7/10 = 70/100, and adding fractions such as 7/10 + 12/100 = 82/100. Learn more: Adding tenths and hundredths together
- Writing tenths and hundredths in decimal notation, as in 9/100 = 0.09, and locating decimals on a number line. Learn more: Writing fractions as decimals, like 0.62
- Comparing decimals to the hundredths place by thinking about size, such as seeing that 0.4 is greater than 0.38. Learn more: Comparing decimals like 0.09 and 0.1
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
How many hundredths make the same amount as 1/10?
- 1
- 10
- 100
How you can help
- Count coins if you have them: 2 dimes and 5 pennies make $0.25, so ask your child to write the amount as a fraction of a dollar too.
- Compare race times from a sports broadcast, such as 9.58 and 9.63 seconds, and ask your child which is less and how they know.
- Use a tape measure with centimeters: 100 centimeters make a meter, so ask your child to find 0.3 meter and 0.25 meter and say which is longer.
Where kids can get stuck
- Swinging to the rule that the shorter decimal always wins, and then saying 0.4 is greater than 0.45.
- Writing 9/100 as 0.9, leaving out the zero in the tenths place, which makes it ten times too big.
- Thinking 4/100 is greater than 3/10 because both of its numbers are bigger.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- decimal
- A number written with a decimal point to show tenths and hundredths, such as 0.45.
- decimal point
- The dot that separates whole numbers from tenths and hundredths.
- tenth
- One of 10 equal parts of a whole, written 1/10 or 0.1.
- hundredth
- One of 100 equal parts of a whole, written 1/100 or 0.01.
- tenths place
- The first place to the right of the decimal point.
- hundredths place
- The second place to the right of the decimal point.
- equivalent
- Having the same value, as 0.5 and 0.50 do.
- compare
- To decide which of two numbers is greater, or whether they are equal.
Ready to build your child’s confidence with decimals to hundredths?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
Join the club
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does Reveal Math Grade 4 Unit 9 cover?
Reveal Math Grade 4 Unit 9 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.