What your child should know in math, grade by grade (K to 5)

Report cards say "approaching standard" or "meets expectations", and most parents have no idea what the standard is. This guide translates it. It follows the Common Core State Standards for Mathematics, which most states use directly or under another name¹⁰. If your state has its own (Texas, Virginia and Florida do, among others), the big ideas by grade are very similar.

For each grade you get the big ideas, what kids should know by heart, and a quick way to check at home.

Kindergarten math

Big ideas: counting, showing and comparing whole numbers (with objects first), and describing shapes and space. The standards say kindergarten should spend more time on number than on anything else¹.

• Count to 100 by ones and by tens.
• Count a group of objects and know the last number said is "how many".
• Compare two groups and say which has more.
• Add and subtract within 10 with objects and drawings.
• By heart: add and subtract within 5 fluently (K.OA.A.5).

Quick check: put 7 grapes on the table. Eat 2 yourself. "How many now?" Can they answer without counting them all again?

1st grade math

Big ideas: addition and subtraction strategies within 20, tens and ones (place value), measuring length, and putting shapes together to make new ones².

• Add and subtract within 20 with strategies like counting on, making ten and doubles.
• Know that 37 is 3 tens and 7 ones.
• Add a two-digit number and a one-digit number, or a multiple of ten, within 100.
• Tell time to the hour and half hour.
• By heart: add and subtract within 10 fluently (1.OA.C.6).

Quick check: "What's 8 + 5?" Watch how they get there. Making ten (8 + 2 + 3) or counting on from 8 are both great signs. If they count from 1 every time, they need more strategy practice.

2nd grade math

Big ideas: place value to 1,000, fluent addition and subtraction within 100, standard units of measurement, and describing shapes³.

• Read, write and compare numbers to 1,000.
• Add and subtract within 100 fluently, and within 1,000 using place value.
• Measure in inches, feet, centimeters and meters.
• Tell time to five minutes, and solve problems with dollars and cents.
• By heart: every sum of two one-digit numbers, like 7 + 8 and 9 + 6, by the end of the year (2.OA.B.2)⁷.

Quick check: "What's 46 + 27?" A child with good place value thinks: 40 and 20 is 60, 6 and 7 is 13, so 73.

3rd grade math

Big ideas: multiplication and division within 100, fractions (especially unit fractions like 1/4), area, and two-dimensional shapes⁴.

• Understand multiplication as equal groups and arrays.
• Understand division as sharing, and as multiplication run backwards.
• See fractions as numbers on a number line, and compare simple fractions.
• Find area by counting squares, then by multiplying.
• Add and subtract within 1,000 fluently.
• By heart: every product of two one-digit numbers by the end of the year (3.OA.C.7)⁸.

Quick check: "Which is bigger, 1/3 or 1/4 of a pizza?" Lots of kids say 1/4, because 4 is bigger than 3. Understanding why it's the other way round is the heart of 3rd grade fractions. A real pizza helps.

4th grade math

Big ideas: multi-digit multiplication and division, equivalent fractions and adding fractions with the same denominator, and sorting shapes by their properties⁵.

• Multiply a number of up to four digits by a one-digit number, and multiply two two-digit numbers.
• Divide numbers of up to four digits by a one-digit number, with remainders.
• Recognize equivalent fractions (2/4 = 1/2) and compare fractions.
• Add and subtract fractions with the same denominator, and multiply a fraction by a whole number.
• Understand decimals to hundredths.
• Fluently: add and subtract multi-digit numbers with the standard algorithm (4.NBT.B.4).

Quick check: "Is 3/6 the same as 1/2? How do you know?" A drawing is a perfect answer.

5th grade math

Big ideas: adding and subtracting fractions with different denominators, multiplying and dividing fractions in simple cases, dividing by two-digit numbers, decimals to hundredths, and volume⁶.

• Add and subtract fractions with unlike denominators (1/2 + 1/3).
• Multiply fractions, and divide unit fractions by whole numbers.
• Add, subtract, multiply and divide decimals to hundredths.
• Find the volume of a rectangular box.
• Plot points on a coordinate plane.
• Fluently: multiply multi-digit whole numbers with the standard algorithm (5.NBT.B.5).

Quick check: "A recipe needs 3/4 cup of flour. We're making half the recipe. How much flour?" (3/8 of a cup.)

The whole picture in one table

How US kids are doing

On the 2024 National Assessment of Educational Progress, 39% of 4th graders scored at or above proficient in math. That's up from 2022 but still below 2019, and 24% scored below basic⁹. Most of the gains came from middle and higher performers. The lowest performers didn't improve. So if your child is struggling, they're far from alone, and the earlier you find the gap, the easier it is to close.

For comparison, kids in England are expected to know their times tables up to 12 x 12 by the end of Year 4, and they take a national multiplication check that year¹¹.

How to help at home without worksheets

• Talk math in daily life: prices at the store, recipes, how long until dinner, splitting snacks fairly.
• Go back before you go forward. If 3rd grade multiplication is hard, check 2nd grade addition facts and place value first.
• Ask how, not just what. "How did you get that?" builds strategy. Our 7 + 4 example shows it.
• Little and often. Ten minutes a day beats an hour on Sunday.
• Watch the feelings. If math has turned into a fight, read how to help a child who hates math.

We use the same idea at Marble, the interactive learning world we build for kids aged 6 to 12. Its quests are about science, making things, creativity and social skills, and each one is pitched just past what that child has already mastered, so it lands at the right level instead of at random.

Questions parents ask

What math should a 2nd grader know?

By the end of 2nd grade, kids are expected to know from memory every sum of two one-digit numbers (like 7 + 8), add and subtract within 20 with mental strategies, and add and subtract within 100 fluently using place value. They also work with numbers to 1,000, measure length in standard units, tell time to five minutes and count money.

When should kids know their times tables?

Common Core expects kids to know every product of two one-digit numbers (up to 9 x 9) from memory by the end of 3rd grade. England's national curriculum goes further: times tables up to 12 x 12 by the end of Year 4.

What if my child is behind in math?

Find the earliest gap instead of drilling the current grade. Most struggles in later grades go back to place value, addition facts or fractions. Practice a little every day, use objects and drawings, talk about math in everyday life, and ask the teacher which skills to work on first.

Does my state use Common Core math?

Most states use the Common Core math standards or close versions of them, sometimes under another name. Some states never adopted them or replaced them, including Texas (TEKS), Virginia (SOL), Florida (B.E.S.T.), Indiana, Oklahoma and South Carolina. The big ideas by grade are similar across states.

What is the hardest grade for math in elementary school?

Many teachers say 3rd and 4th grade. Multiplication, division and fractions arrive together, and kids have to move from counting-based strategies to place value and multiplicative thinking. Solid addition facts and a real grasp of place value before 3rd grade make that jump much easier.

Sources

1. Common Core State Standards: Kindergarten math introduction
2. Common Core State Standards: Grade 1 math introduction
3. Common Core State Standards: Grade 2 math introduction
4. Common Core State Standards: Grade 3 math introduction
5. Common Core State Standards: Grade 4 math introduction
6. Common Core State Standards: Grade 5 math introduction
7. Common Core State Standards: Grade 2 Operations and Algebraic Thinking (2.OA.B.2)
8. Common Core State Standards: Grade 3 Operations and Algebraic Thinking (3.OA.C.7)
9. The Nation's Report Card: 2024 NAEP mathematics, grade 4
10. The 74: Fifteen years later, Common Core math endures in many states (2025)
11. UK Department for Education: Multiplication tables check attainment