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Grade 3 Math Study Guide

Alpha School · Math · built 2 October 2026

This guide covers the eight skills that the Grade 3 math test leans on hardest. Each one starts with something you can already do, adds one new move, and then gives you practice that climbs.

Every question here is new. None of them is from a test. The numbers and stories are different on purpose, so what you are practicing is the method, not the answer.

How to use it: answer a question, press Check, then read the answer even when you were right. The answer tells you where the wrong choices come from, and that is the part worth knowing on test day. Your work saves in this browser, so you can stop and come back.

In this guide

1. Place value to 100,000

Start here

What is 300 + 40 + 2?

300 is 3 hundreds. 40 is 4 tens. 2 is 2 ones.

300 + 40 + 2 = 342.

Each number in that sum fills one place. That is all expanded form is: the number taken apart, one place at a time.

The new part

Now a bigger one, with a hole in it.

50,000 + 2,000 + 60 + 7

Ten thousands: 5. Thousands: 2. Hundreds: nothing is listed. Tens: 6. Ones: 7.

The hundreds place still exists. It needs a digit, so it gets a 0.

50,000 + 2,000 + 60 + 7 = 52,067.

The same number can be described in words more than one way. 52,067 is "fifty-two thousand, sixty-seven". It is also "5 ten thousands, 2 thousands, 6 tens, and 7 ones", and "52 thousands and 67 ones". A description is wrong only if one of its pieces lands in the wrong place.

To put numbers in order, count the digits first. More digits means a bigger number. If two numbers have the same number of digits, compare from the left, one place at a time, and stop at the first place that differs.

The rule

Every place gets a digit. If a place has nothing in it, write 0 to hold it.

To order: more digits wins; same digits, compare from the left.

Watch out for

Skipping the empty place. 50,000 + 2,000 + 60 + 7 looks like four pieces, so it is tempting to write four digits: 5,267. But the hundreds place is still there, empty. Writing a 0 in it is what keeps the 5 in the ten thousands place.

Reading a description too fast. "3 ten thousands, 6 thousands, 4 tens, 8 ones" and "30,000 + 6,000 + 400 + 8" look alike. One of them has moved the 4 into the hundreds. Check each piece against its place.

Practice

  1. What is 600 + 50 + 3?

    Standard form
  2. Which expanded form shows 40,315?

    Expanded form
  3. The expanded form of a number is 70,000 + 800 + 9. What is the standard form?

    Standard form
  4. Which answer choice does NOT describe the number 36,048?

    Does NOT describe it

2. Add and subtract within 1,000

Start here

What is 400 + 300?

4 hundreds plus 3 hundreds is 7 hundreds.

400 + 300 = 700.

So 425 + 300 is 725. Adding hundreds leaves the tens and ones alone.

The new part

Test stories usually have two steps. Here is one.

Maya had $348 in her account. She earned $125 more. Then she spent $160 on a skateboard. How much is in her account now?

Earned more: add. Spent: minus. Write the equation in the order the story happens.

348 + 125 − 160 = □

Now one step at a time.

348 + 125 = 473.

473 − 160 = 313.

Maya has $313.

When the test asks "which equation can be used", it wants that first line, before any arithmetic. When it asks for the amount, it wants the last line.

The rule

One story, one step at a time. "More", "earned", "put in" means add. "Spent", "took out", "gave away" means minus. Write the equation in story order, then work it down line by line.

Watch out for

Stopping after one step. 473 is a real number from the story, and it will be one of the choices. It is not the answer to the question asked.

Subtracting the small digit from the big digit in each column. In 612 − 478, the ones column is 2 minus 8. You cannot take 8 from 2, so you rename a ten. A student who writes 8 minus 2 = 6 in the ones gets an answer that is too big, every time.

Practice

  1. Two quick ones.

    a) 536 + 200
    b) 536 − 300
  2. Jonah had 215 stickers. He got 140 more for his birthday. Then he gave 85 to his sister. Which equation can be used to find how many stickers Jonah has now?

    Equation
  3. Now work Jonah's equation. How many stickers does he have?

    Stickers
  4. Priya's class collected 612 cans in September and 478 cans in October. How many more cans did the class collect in September than in October?

    More cans

Mixed check 1

Mixed check 1

These two questions do not say which skill they use. Decide the method first, then answer.

  1. Which list shows these numbers in order from greatest to least? 9,870 · 10,089 · 9,978 · 10,809

    Which method does this need?
    Greatest to least
  2. Kai had $507. He spent $189 on a bike helmet. Then he earned $45 mowing a lawn. How much money does Kai have now?

    Which method does this need?
    Dollars

3. Multiplication: equal groups, tables and times as many

Start here

There are 3 boxes of crayons with 5 crayons in each box. How many crayons?

Count by fives, once for each box: 5, 10, 15.

3 × 5 = 15.

3 groups, 5 in each group, 15 in all. That is what the × sign says.

The new part

The test likes to hide equal groups inside a table.

BoxesCrayons
15
210
315
420

Each row is boxes × 5. 1 × 5 = 5. 2 × 5 = 10. 4 × 5 = 20.

A table that says 1 → 6, 2 → 7, 3 → 8 is adding 5 to the box number. That is not groups of 5.

The other place multiplication hides is the phrase times as many.

There are 4 red pens. There are 3 times as many blue pens as red pens.

3 × 4 = 12. There are 12 blue pens.

"3 times as many" is three groups of 4. It is not "3 more than 4", which would be 7.

One more place: a strip diagram. Six equal parts in a bar, each labeled 9, with a question mark over the whole bar, means 6 × 9.

And odd or even is about the ones digit only. 3,721 is odd because it ends in 1, even though there is a 2 in it.

The rule

Equal groups means multiply: groups × in each group = total.

"Times as many" is multiplying. "More than" is adding. Even numbers end in 0, 2, 4, 6 or 8.

Watch out for

Reading 3 × 4 as "3 more". The statement "there are 3 more blue pens" sounds right and is one of the choices. The expression 3 × 4 says 3 groups of 4.

A table that adds. The wrong table goes up by the right amount but starts in the wrong place. Check the first row: 1 box should be 5 crayons, not 6.

Practice

  1. Two quick ones.

    a) 6 × 7
    b) Which number is odd?
  2. There are 8 markers in each pack. Which table shows the relationship between the number of packs and the number of markers?

    Table
  3. Lena made 6 bracelets. She used 9 beads for each bracelet. Which strip diagram can be used to find the number of beads Lena used?

    Strip diagram
  4. There are 7 oak trees in a park. The expression 4 × 7 represents the number of pine trees in the park.

    Which statement is true?
    How many pine trees?

4. Division: sharing, grouping and the missing factor

Start here

What number times 4 equals 24?

4 × 6 = 24, so the missing number is 6.

You already know the fact. Division is just asking for the factor you cannot see.

24 ÷ 4 = 6.

The new part

Two stories, same numbers, same equation, different meaning.

Sharing: 24 cookies are shared equally by 4 children. How many does each child get?

24 ÷ 4 = 6. Each child gets 6 cookies.

Grouping: 24 cookies are put in bags of 4. How many bags?

24 ÷ 4 = 6. There are 6 bags.

Either way, the total is split by the thing you know, and the answer is the thing you do not know.

The test's favorite trick is to hide the total. "3 teams of 8 players are split into 4 equal groups." Nobody said 24. You have to make it.

3 × 8 = 24 players in all.

24 ÷ 4 = 6 players in each group.

The rule

Total ÷ what you know = what you want. If the story gives you groups instead of a total, multiply to find the total first.

Watch out for

Dividing the first two numbers you see. In the teams story, 8 ÷ 4 = 2 uses two numbers from the story and ignores the third. Ask: is 8 the total? No, 8 is one team. The total has to be built.

Mixing up ÷ and ×. A story that ends "how many cups" when you know the total and the size of each cup is division, even though the numbers get smaller.

Practice

  1. 7 × □ = 56. What is the missing number?

    Missing number
  2. Deshawn poured 42 ounces of juice into cups. He put 6 ounces in each cup. Which equation can be used to find the number of cups Deshawn filled?

    Equation
  3. Marisol has 45 trading cards. She shares them equally among 5 friends. How many cards does each friend get?

    Cards each
  4. There are 2 vans going to a museum. Each van carries 9 students. At the museum, all the students are split into 3 equal groups. How many students are in each group?

    Students in each group

Mixed check 2

Mixed check 2

These three questions do not say which skill they use. Decide the method first, then answer.

  1. A bakery puts 6 muffins in each box. It fills 9 boxes. How many muffins is that?

    Which method does this need?
    Muffins
  2. There are 48 chairs set up in 6 equal rows. How many chairs are in each row?

    Which method does this need?
    Chairs in each row
  3. Elena had 356 beads. She used 128 of them for a necklace. Then she bought 200 more. How many beads does she have now?

    Which method does this need?
    Beads

5. Fractions on a number line and equivalent fractions

Start here

A number line from 0 to 1 is cut into 4 equal parts. How big is each part?

011/4

Each part is one fourth: 1/4.

The marks from left to right are 1/4, 2/4, 3/4, and then 1, which is 4/4.

The new part

Now cut the same line into 8 equal parts as well. Quarters are marked above the line and eighths below it.

01P

Point P is 2 quarter-marks from 0, so P is 2/4.

Count the eighth-marks below: P is 4 of them from 0, so P is also 4/8.

Same point, two names. 2/4 and 4/8 are equivalent. So is 1/2.

When a question says "ride 2/3 of a mile, which number line shows the point", look for two things: the line between 0 and 1 is cut into 3 equal parts, and the point sits on the second mark.

The rule

The bottom number is how many equal parts between 0 and 1. The top number is how many parts you count from 0. Two fractions sitting on the same point are equivalent.

Watch out for

Counting tick marks instead of parts. A line cut into 4 parts has 5 tick marks, counting the ends. A point on the third mark after 0 is 3/4, not 3/5. Count the spaces, not the lines.

A line that goes past 1. If the line runs from 0 to 2, the parts between 0 and 1 are what the bottom number counts, not all the parts you can see.

Practice

  1. Point A is shown on the number line.

    01A

    What fraction does point A represent?

    Fraction
  2. You want to show 5/6 on a number line from 0 to 1.

    How many equal parts between 0 and 1?
    The point is how many parts from 0?
  3. Point K is shown. Fourths are marked above the line and eighths below it.

    01K

    Point K represents two equivalent fractions. Which two?

    Two equivalent fractions
  4. A number line from 0 to 1 is cut into 6 equal parts. Omar says the point halfway along it represents 3/6. His friend says the same point represents 1/2.

    Who is right?

6. Comparing fractions

Start here

You can have 1/3 of a pizza or 1/8 of the same pizza. Which piece is bigger?

Cutting a pizza into 3 pieces makes big pieces. Cutting it into 8 makes small ones.

1/3 is greater than 1/8.

A bigger bottom number means more cuts, so smaller pieces.

The new part

There are two kinds of comparison on the test, and each has one thing to look at.

3/63/8

Same top number: 3/6 and 3/8. Three pieces each. Sixths are bigger pieces than eighths.

3/6 is greater than 3/8, because sixths are larger than eighths.

5/83/8

Same bottom number: 5/8 and 3/8. The pieces are the same size. Five of them is more than three.

5/8 is greater than 3/8, because 5 pieces is more than 3 pieces of the same size.

The test asks for the comparison and the reason. Your reason has to say which pieces are bigger, or which count is bigger.

The rule

Same bottom: more pieces is more. Same top: the smaller bottom number is bigger, because its pieces are bigger.

Comparing only works when both fractions are of the same-size whole.

Watch out for

"8 is bigger than 6, so eighths are bigger." It is the most natural thing to think, and it is backwards. More cuts, smaller pieces.

Different wholes. 3/8 of a small pizza and 3/8 of a large pizza are not the same amount of pizza. If the wholes are different sizes, the fractions cannot be compared.

Practice

  1. Which is greater, 1/4 or 1/6?

    Greater
  2. You need to compare 2/3 and 2/5. What should you look at?

    Look at
  3. Fraction strips are shown.

    4/64/8

    Which comparison and explanation are true?

    Comparison
  4. Tara ate 3/8 of a small pizza. Ben ate 3/8 of a large pizza. Tara says they ate the same amount of pizza.

    Is Tara right?
    Which is greater, 5/8 or 7/8?

Mixed check 3

Mixed check 3

These three questions do not say which skill they use. Decide the method first, then answer.

  1. A number line from 0 to 1 is cut into 8 equal parts. Point R is 6 parts from 0. Which two fractions can point R represent?

    Which method does this need?
    Two fractions
  2. Which comparison is true?

    Which method does this need?
    2/6 and 2/4
  3. A classroom has 4 tables. Each table has 7 chairs. All the chairs are moved into 2 equal rows for an assembly. How many chairs are in each row?

    Which method does this need?
    Chairs in each row

7. Perimeter and area

Start here

A rectangle is 5 cm long and 3 cm wide. If you walk all the way around it, how far do you walk?

5 cm3 cm

Four sides: 5, 3, 5, 3.

5 + 3 + 5 + 3 = 16.

The perimeter is 16 cm. Perimeter is the distance around.

The new part

A square only shows you one side. The other three are the same length, even though they are not labeled.

7 cm

7 + 7 + 7 + 7 = 28.

Or 4 × 7 = 28.

The perimeter is 28 cm.

Area is a different question: how many squares fit inside.

3 rows of 5 squares. 3 × 5 = 15.

The area is 15 square units. Perimeter is measured in cm; area is measured in square cm, because you are counting squares.

Two different shapes can have the same area. A 2 by 6 rectangle and a 3 by 4 rectangle both cover 12 squares.

The rule

Perimeter is the distance around: add every side, including the ones not labeled.

Area is the squares inside: rows × squares in each row.

Watch out for

Adding only the sides you can see. A square labeled 12 has four sides of 12. Adding 12 + 12 gives you half the fence.

Multiplying for perimeter. 12 × 12 = 144 is the area of that square, not its perimeter. If the question says "around", add.

Practice

  1. A square has sides of 9 inches. What is 9 + 9 + 9 + 9?

    Sum
  2. A rectangle is shown.

    8 m3 m
    Which expression gives the perimeter?
    Which expression gives the area?
  3. The shaded figure on the grid is Noor's garden. Each square is 1 square meter.

    Area in square meters
    Perimeter in meters
  4. A square garden has one side labeled 12 feet. Jules says the perimeter is 24 feet, because 12 + 12 = 24. What is the perimeter of the garden?

    Perimeter in feet

8. Reading pictographs, dot plots and bar graphs

Start here

A pictograph row for "Mystery books" shows ●●●●. The key says ● = 2 books. How many mystery books?

4 symbols, each worth 2.

4 × 2 = 8 mystery books.

Read the key before you count anything.

The new part

A dot plot puts one dot above a number for each thing counted. This table and dot plot show the same data.

Pets at homeNumber of students
03
15
22
31
0123Pets at home

Five students have 1 pet, so there are 5 dots above the 1. Every dot is one student.

How many students have more than 1 pet? Count the dots above 2 and above 3: 2 + 1 = 3 students.

A bar graph has a scale on the side. If the lines go 0, 5, 10, 15, a bar that stops halfway between 10 and 15 is about 12 or 13, not 11.

When the test asks "which answer choice does NOT represent the table", check every row of every choice against the table. The wrong one usually has the right shape with one number off, or ignores its own key.

The rule

Read the key or the scale first. Then check every row, not just the first one.

Watch out for

Counting symbols as 1 each. If the key says ● = 4, then ●●● is 12, not 3. A pictograph that draws 12 symbols for 12 items when its key says 4 each is wrong, even though 12 is the right number.

Reading a scale of 2 as 1. Look at the gap between the numbers on the side before you read a bar.

Practice

  1. A pictograph key says ● = 5 marbles. The row for "Red" shows ●●●. How many red marbles?

    Red marbles
  2. In another pictograph, each ★ stands for 4 shells. Nia found 20 shells. How many ★ should be in Nia's row?

    Stars
  3. The dot plot shows how many goals each player on a team scored this season.

    01234Goals scored
    How many players scored more than 1 goal?
    How many players are on the team?
  4. The table shows the favorite fruit of the students in a class.

    FruitStudents
    Apple12
    Banana8
    Grape4

    Which answer choice does NOT represent the information in the table?

    Does NOT represent the table

Mixed run

Mixed run

Every skill in this guide, in no order, and nothing tells you which one to use. Name the method on your paper before you work it. That is exactly what the test asks.

  1. The expanded form of a number is 90,000 + 4,000 + 30 + 1. What is the standard form?

    Standard form
  2. A rectangular rug is 9 feet long and 4 feet wide. What is the perimeter of the rug in feet?

    Perimeter in feet
  3. The same rug is 9 feet long and 4 feet wide. What is the area of the rug in square feet?

    Area in square feet
  4. Priya has 6 marbles. Theo has 4 times as many marbles as Priya. How many marbles does Theo have?

    Marbles
  5. Priya has 6 marbles. Theo has 4 more marbles than Priya. How many marbles does Theo have?

    Marbles
  6. A library has 5 shelves of picture books with 8 books on each shelf. All the picture books are shared equally among 4 classrooms. How many books does each classroom get?

    Books per classroom
  7. Which comparison is true?

    5/6 and 5/8
  8. Point D is shown on the number line.

    01D

    What fraction does point D represent?

    Fraction
  9. The pictograph shows how many cars were washed at a fundraiser.

    Saturday♦♦♦♦
    Sunday♦♦

    Key: ♦ = 3 cars

    How many more cars were washed on Saturday than on Sunday?

    More cars
  10. Which answer choice does NOT describe the number 70,205?

    Does NOT describe it

The day before

Read this once, cold. The first move of each skill, then a few habits.

SkillFirst move
Place valueSay each digit's place. An empty place gets a 0. To order, count digits first.
Add and subtractWrite the whole equation in story order before you add or subtract anything.
Equal groupsAsk: how many groups, how many in each? Groups × each = total. "Times as many" multiplies.
DivisionFind the total first. Then total ÷ what you know = what you want.
Fractions on a lineCount the equal parts between 0 and 1 (bottom number). Count parts from 0 (top number).
Comparing fractionsSame bottom: more pieces wins. Same top: smaller bottom wins, because its pieces are bigger.
Perimeter and area"Around" means add every side, even the unlabeled ones. "Square units" means rows × columns.
Reading dataRead the key or the scale before counting a single symbol or bar.

Habits