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  1. ISEE Lower Level Mathematics Achievement
  2. Choose an Equation That Represents a Situation

5 + ? = 123 × 4 = 1215 − 6 = ?
ISEE LOWER LEVEL • MATHEMATICS ACHIEVEMENT

Choose an Equation That Represents a Situation

Learn how to turn a word problem into a math equation you can solve!

SECTION 1

Why Do We Write Equations?

People have been solving word problems for thousands of years! Long ago, farmers needed to figure out how much grain they had left after selling some. Shopkeepers had to calculate how much money a customer owed. They all needed a way to organize their thinking.

An equation is a math sentence that uses numbers and symbols. It helps us take a story or situation and turn it into math we can solve. Let's see how this idea grew over time!

2000 BC
Ancient Babylonians
Babylonian scribes wrote word problems on clay tablets. They figured out missing amounts using clever number tricks!
300 AD
Diophantus of Alexandria
A Greek mathematician started using letters to stand for unknown numbers. This was a huge step toward modern equations!
1600s
The Equals Sign Is Born
Robert Recorde invented the equals sign (=). Now people could write neat math sentences like 3 + 4 = 7.
Today
Equations Are Everywhere
You use equations in school, in science, and even when figuring out how to spend your allowance. The ISEE tests this skill too!

On the ISEE, you will read a short story or situation. Then you pick the equation that matches it. Let's learn how to do that step by step!

SECTION 2

Core Ideas You Need to Know

Before we practice, let's nail down some key ideas. These are the building blocks for choosing the right equation.

1

Know Your Operations

Addition (+) means combining or putting together. Subtraction (−) means taking away or finding a difference. Multiplication (×) means equal groups. Division (÷) means splitting into equal parts.
2

Look for Clue Words

Words like "in all" and "total" often mean add. Words like "left" and "fewer" often mean subtract. Words like "each" and "every" often mean multiply or divide.
3

Identify the Unknown

The unknown is the number you don't know yet. It might be shown as a question mark (?), a blank, or a letter like n. Your equation should help you find it.
4

Check That It Makes Sense

After you pick an equation, ask yourself: Does this match the story? If the story says someone gives away apples, you should see subtraction, not addition.
✦ KEY TAKEAWAY
Think of an equation like a recipe. A recipe turns ingredients into a dish. An equation turns a word problem into math. You just need to match the right ingredients (numbers) with the right instructions (operation)!
SECTION 3

See How Words Become Equations

Let's look at a diagram that shows how to go from a word problem to an equation. Follow the arrows from left to right!

From Words to an Equation: 3 StepsSTEP 1Read the story."Sam has 8 stickers.He gives 3 away.How many are left?"STEP 2Find clue words."gives away" → subtract"how many left" → subtractNumbers: 8 and 3STEP 3Write the equation!8 − 3 = ?Answer: 5 stickersCommon Clue WordsAddition (+)in alltotalcombinedaltogethersumSubtraction (−)leftfewergave awaydifferenceremainMultiplication (×)eacheverytimesgroups ofperDivision (÷)split equallyshareddividedhow many in eachper group
This diagram shows the three steps: read the story, find clue words, and write the equation. The bottom boxes show common clue words for each operation.

The top row shows the three steps. First, you read the story carefully. Next, you circle or underline the clue words that tell you which operation to use. Finally, you write the equation with the correct numbers and symbol.

The bottom row shows clue words for each operation. Keep these in mind when you read ISEE problems!

SECTION 4

The Four Types of Equations

On the ISEE, word problems usually need one of four operations. Let's see what each equation looks like. The question mark shows the unknown — the number you need to find.

ADDITION
part + part = total
Use when you are combining two amounts. Example: 7 + 5 = ?
SUBTRACTION
total − part = part left
Use when you are taking away or finding a difference. Example: 12 − 4 = ?
MULTIPLICATION
number of groups × amount in each group = total
Use when you have equal groups. Example: 3 × 6 = ?
DIVISION
total ÷ number of groups = amount in each group
Use when you are splitting equally. Example: 20 ÷ 4 = ?
💡 ISEE Test Tip
On the ISEE, the answer choices are four different equations. Read the word problem first, decide which operation makes sense, and then look for that operation in the choices. This saves time!
SECTION 5

A Closer Look at Clue Words

Clue words are like a treasure map. They point you to the right operation! Let's organize them in a handy table.

Clue words and example sentences for each operation
OperationClue WordsExample Sentence
Addition (+)in all, total, altogether, combined, sum, both, moreJill has 4 red pens and 6 blue pens. How many pens does she have in all?
Subtraction (−)left, fewer, gave away, remain, difference, less thanTom had 15 grapes. He ate 7. How many grapes are left?
Multiplication (×)each, every, times, groups of, per, rows ofThere are 5 bags with 4 apples in each bag. How many apples in all?
Division (÷)share equally, split, divided, each gets, per group24 stickers are shared equally among 6 friends. How many does each friend get?
Example: Matching a Story to an Equation"Maya had 20 stickers. She gave 8 stickers to her friend.""How many stickers does Maya have now?"Find the clue words!"gave" → take away → SUBTRACTIONWhich equation matches?20 + 8 = ?A ✗ (adding)20 − 8 = ?B ✓ Correct!20 × 8 = ?C ✗ (multiplying)20 ÷ 8 = ?D ✗ (dividing)Maya gave stickers away, so we subtract. 20 − 8 = 12 stickers!
This diagram shows a full example. The story has the clue word "gave," which tells us to subtract. Choice B (20 − 8 = ?) is correct.
⚠️ Watch Out!
Some clue words can be tricky. The word "more" can mean addition ("5 more than 3" → 3 + 5) or comparison ("how many more" → subtraction). Always re-read the whole sentence before picking an operation.
SECTION 6

Worked Example: Step by Step

Let's walk through a problem together, just like you would on the ISEE. Follow each step carefully!

Problem: There are 6 shelves in a bookcase. Each shelf holds 8 books. Which equation shows how to find the total number of books?

(A) 6 + 8 = ? (B) 8 − 6 = ? (C) 6 × 8 = ? (D) 8 ÷ 6 = ?

Finding the Right Equation

Step 1 — Read the problem carefully

There are 6 shelves. Each shelf holds 8 books. We need to find the total number of books.

Step 2 — Circle the clue words

The word "each" is a big clue. It tells us we have equal groups. Six shelves that each hold the same amount means we should multiply.

Step 3 — Identify the numbers

The two numbers in the problem are 6 (shelves) and 8 (books per shelf).

Step 4 — Build the equation

Number of groups × amount in each group = total. So the equation is 6 × 8 = ?.
The answer is (C) 6 × 8 = ?

Step 5 — Check your answer

Does multiplying make sense? Yes! 6 groups of 8 is 48 books total. Addition would only give us 14, which is too small. Subtraction and division don't match the story at all. We got it right!
SECTION 7

Common Mistakes and How to Avoid Them

Even great students make mistakes on these problems. Here are the most common ones and how to avoid them.

Common mistakes and solutions
MistakeWhy It HappensHow to Fix It
Picking addition when the story says "take away"Rushing through the problemUnderline the clue words before looking at the answer choices.
Confusing multiplication and additionBoth can give a bigger number, so they seem similarAsk: Are there equal groups? If yes, multiply. If you're just combining two different amounts, add.
Putting numbers in the wrong order for subtractionNot thinking about which number is biggerIn subtraction, the bigger number (the total you started with) always comes first.
Not reading all four answer choicesPicking the first choice that looks rightAlways read all four choices. Two might use the same numbers but different operations!
✦ KEY TAKEAWAY
Think of choosing an equation like choosing a tool from a toolbox. You wouldn't use a hammer to screw in a screw! The clue words tell you which tool (operation) fits the job.
SECTION 8

Building Toward Harder Problems

Right now, most ISEE problems ask you to pick an equation with one operation. As you grow as a math student, problems will get more interesting. Let's see how this skill grows.

How this skill grows over time
What You Know NowWhat Comes Next
One-step equations (one operation)Two-step equations (two operations)
Using a ? for the unknownUsing letters like x or n for unknowns
Choosing the equation from a listWriting your own equation from scratch
Simple whole numbersFractions and decimals in equations

Every big math skill starts with a small step. Choosing the right equation is one of those important first steps. You're building a strong foundation!

SECTION 9

Practice Problems

Now it's your turn! Read each problem carefully, find the clue words, and pick the equation that matches the story. Remember: there is no penalty for guessing on the ISEE, so always pick an answer!

PROBLEM 1 — CONCEPTUAL
Emma has 9 crayons. Her mom gives her 6 more crayons. Which equation shows how to find the total number of crayons Emma has now? (A) 9 − 6 = ? (B) 9 + 6 = ? (C) 9 × 6 = ? (D) 9 ÷ 6 = ?
PROBLEM 2 — BASIC CALCULATION
A baker made 24 cookies. He sold 9 cookies. Which equation shows how to find how many cookies the baker has left? (A) 9 + 24 = ? (B) 24 × 9 = ? (C) 24 − 9 = ? (D) 24 ÷ 9 = ?
PROBLEM 3 — INTERMEDIATE
A classroom has 4 rows of desks. Each row has 7 desks. Which equation can be used to find the total number of desks? (A) 4 + 7 = ? (B) 4 × 7 = ? (C) 7 − 4 = ? (D) 28 ÷ 7 = ?
PROBLEM 4 — APPLIED
Ms. Garcia has 30 pencils to share equally among 5 students. Which equation shows how to find the number of pencils each student gets? (A) 5 × 30 = ? (B) 30 + 5 = ? (C) 30 − 5 = ? (D) 30 ÷ 5 = ?
PROBLEM 5 — CRITICAL THINKING
Jake collected 14 seashells on Saturday and some more on Sunday. He now has 23 seashells altogether. Which equation can be used to find how many seashells Jake collected on Sunday? (A) 14 + ? = 23 (B) 14 + 23 = ? (C) 23 × 14 = ? (D) 14 − ? = 23
SUMMARY

Let's Review!

To choose the right equation for a situation, follow three steps. First, read the problem carefully and find the numbers. Next, look for clue words that tell you which operation to use: addition for combining, subtraction for taking away, multiplication for equal groups, and division for splitting equally. Finally, pick the equation that uses the correct numbers and operation.

Remember to check your answer by asking, "Does this equation match the story?" On the ISEE, always answer every question — there is no penalty for guessing. Use process of elimination to cross out choices that use the wrong operation. You've got this!

Varsity Tutors • ISEE Lower Level • Choose an Equation That Represents a Situation