Mathematics: Fractions – Grade 3

Unit fractions are the building blocks of all fractions! A unit fraction is a fraction that has 1 as its numerator (the top number) and represents exactly one equal part of a whole. Let's explore how these special fractions work.

Every unit fraction follows the pattern $\frac{1}{n}$, where the bottom number (called the denominator) tells you how many equal parts the whole was divided into. The top number (called the numerator) is always 1, meaning you're looking at just one of those parts.

For example:

• $\frac{1}{2}$ means 1 part out of 2 equal parts (one-half) 🍕
• $\frac{1}{4}$ means 1 part out of 4 equal parts (one-fourth) 🍫
• $\frac{1}{8}$ means 1 part out of 8 equal parts (one-eighth) 🍰

The equal parts aspect is crucial! If you cut a cookie unevenly, with some pieces bigger than others, you can't use fractions to describe those pieces accurately.

There are several ways to show unit fractions that help you understand what they mean:

Area Models: These use shapes divided into equal regions. If you have a rectangle divided into 3 equal parts and shade 1 part, you've shown $\frac{1}{3}$. The key is that all parts must be exactly the same size.

Set Models: These show fractions using groups of objects. If you have 5 apples 🍎🍎🍎🍎🍎 and circle 1 apple, you've shown $\frac{1}{5}$ of the apples.

Number Line Models: These place fractions on a line between whole numbers. To show $\frac{1}{4}$ on a number line, you divide the space between 0 and 1 into 4 equal parts and mark the first division point.

Here's something that might surprise you: the bigger the denominator gets, the smaller each piece becomes! This is different from whole numbers where bigger numbers mean more.

• $\frac{1}{2}$ (one-half) is larger than $\frac{1}{4}$ (one-fourth)
• $\frac{1}{4}$ (one-fourth) is larger than $\frac{1}{8}$ (one-eighth)
• $\frac{1}{8}$ (one-eighth) is larger than $\frac{1}{12}$ (one-twelfth)

Think about pizza slices: if you cut a pizza into 2 pieces, each piece is much bigger than if you cut the same pizza into 12 pieces! 🍕

In Grade 3, you'll work with these specific denominators: 2, 3, 4, 5, 6, 8, 10, and 12. These numbers were chosen because they're easy to visualize and work with using common objects and manipulatives.

Unit fractions appear everywhere in daily life:

• Sharing 1 granola bar equally among 4 friends gives each person $\frac{1}{4}$ of the bar
• Taking 1 slice from a pizza cut into 8 equal pieces means you have $\frac{1}{8}$ of the pizza
• Reading for $\frac{1}{3}$ of an hour means reading for 20 minutes (since 1 hour = 60 minutes, and $60 \div 3 = 20$)

Using precise mathematical language helps you communicate clearly about fractions:

• The numerator is the top number that tells how many parts you have
• The denominator is the bottom number that tells how many equal parts make the whole
• A unit fraction always has 1 as its numerator
• Equal parts means all pieces are exactly the same size

Understanding unit fractions gives you the foundation for working with all other fractions. Every fraction you'll ever encounter can be thought of as a combination of unit fractions added together!

Now that you understand unit fractions, you can discover how all fractions are created! Every fraction is simply the result of adding unit fractions together. This is like building with blocks—unit fractions are your building blocks, and you can combine them to create any fraction you need.

When you add identical unit fractions together, you create larger fractions. Here's how it works:

• $\frac{1}{3} + \frac{1}{3} = \frac{2}{3}$ (two-thirds)
• $\frac{1}{4} + \frac{1}{4} + \frac{1}{4} = \frac{3}{4}$ (three-fourths)
• $\frac{1}{5} + \frac{1}{5} + \frac{1}{5} + \frac{1}{5} + \frac{1}{5} = \frac{5}{5} = 1$ (one whole)

Notice that the denominator (bottom number) stays the same because you're still working with the same size pieces. The numerator (top number) counts how many of those pieces you have.

Using Area Models: Imagine a chocolate bar divided into 6 equal squares. If you eat 1 square, you've eaten $\frac{1}{6}$ of the bar. If you eat 4 squares total, you've eaten $\frac{1}{6} + \frac{1}{6} + \frac{1}{6} + \frac{1}{6} = \frac{4}{6}$ of the chocolate bar! 🍫

Using Number Lines: On a number line, each unit fraction represents a "hop" of the same size. To show $\frac{3}{5}$, you make 3 hops, each of size $\frac{1}{5}$, starting from 0.

Using Set Models: If you have 8 crayons and you use 3 of them, you can think of it as: $\frac{1}{8} + \frac{1}{8} + \frac{1}{8} = \frac{3}{8}$ of your crayons. 🖍️🖍️🖍️

Something exciting happens when you add enough unit fractions together—you can get fractions greater than one whole! This means fractions can represent amounts larger than 1.

For example:

• $\frac{1}{4} + \frac{1}{4} + \frac{1}{4} + \frac{1}{4} + \frac{1}{4} = \frac{5}{4}$

This means you have 5 fourth-sized pieces, which is more than 1 whole (since 1 whole = $\frac{4}{4}$).

Let's say you're making trail mix and each handful represents $\frac{1}{6}$ of your daily snack portion:

• 1 handful = $\frac{1}{6}$
• 2 handfuls = $\frac{1}{6} + \frac{1}{6} = \frac{2}{6}$
• 3 handfuls = $\frac{1}{6} + \frac{1}{6} + \frac{1}{6} = \frac{3}{6}$
• 6 handfuls = $\frac{6}{6} = 1$ (exactly your full daily portion)
• 7 handfuls = $\frac{7}{6}$ (more than your daily portion!)

You can count by unit fractions just like counting by whole numbers:

Counting by $\frac{1}{3}$: $\frac{1}{3}$, $\frac{2}{3}$, $\frac{3}{3}$ (which equals 1), $\frac{4}{3}$, $\frac{5}{3}$, $\frac{6}{3}$ (which equals 2)...

Counting by $\frac{1}{5}$: $\frac{1}{5}$, $\frac{2}{5}$, $\frac{3}{5}$, $\frac{4}{5}$, $\frac{5}{5}$ (which equals 1), $\frac{6}{5}$, $\frac{7}{5}$...

This counting pattern helps you see that fractions follow predictable rules, just like whole numbers do.

Understanding how fractions are built from unit fractions is essential preparation for Grade 4, when you'll learn to add and subtract fractions. For now, focus on seeing the pattern: when you combine unit fractions with the same denominator, you're essentially counting how many of that particular unit fraction you have.

Some students think that fractions greater than 1 aren't "real" fractions, but that's not true! Fractions like $\frac{5}{3}$ and $\frac{7}{4}$ are perfectly valid numbers that represent specific quantities.

Another misconception is thinking you can only add unit fractions. While we focus on unit fractions in this chapter because they're the building blocks, later you'll learn that any fractions with the same denominator can be added together.

Try these activities to strengthen your understanding:

• Use fraction strips or circles to physically combine unit fractions
• Draw area models showing different ways to build the same fraction
• Create number line representations of fraction addition
• Tell stories about real-world situations involving combining equal parts

Just like the number 5 can be written as "five" or "5," fractions can also be expressed in different ways! Learning multiple ways to read and write fractions helps you communicate more clearly about these important numbers and deepens your understanding of what fractions actually represent.

Standard Form uses the familiar fraction bar notation that you see in math textbooks. Examples include:

• $\frac{1}{2}$
• $\frac{3}{4}$
• $\frac{7}{5}$
• $\frac{11}{8}$

This form is compact and efficient for mathematical work, but sometimes it's helpful to express fractions using words.

Word Form expresses fractions entirely in words, following specific naming patterns:

• $\frac{1}{2}$ becomes "one-half"
• $\frac{3}{4}$ becomes "three-fourths"
• $\frac{7}{5}$ becomes "seven-fifths"
• $\frac{11}{8}$ becomes "eleven-eighths"

Numeral-Word Form combines numbers with words for a hybrid approach:

• $\frac{1}{2}$ becomes "1 half"
• $\frac{3}{4}$ becomes "3 fourths"
• $\frac{7}{5}$ becomes "7 fifths"
• $\frac{11}{8}$ becomes "11 eighths"

The denominator determines the name of the fractional unit:

• Denominator 2 → halves
• Denominator 3 → thirds
• Denominator 4 → fourths
• Denominator 5 → fifths
• Denominator 6 → sixths
• Denominator 8 → eighths
• Denominator 10 → tenths
• Denominator 12 → twelfths

The numerator tells you how many of those units you have. So $\frac{5}{8}$ represents "5 eighths" or "five-eighths"—you have 5 pieces, and each piece is an eighth-sized unit.

When the numerator equals the denominator, you have exactly one whole:

• $\frac{4}{4} = 1$ ("four-fourths equals one")
• $\frac{6}{6} = 1$ ("six-sixths equals one")
• $\frac{10}{10} = 1$ ("ten-tenths equals one")

For fractions greater than one, you can express them in word form too:

• $\frac{5}{4}$ = "five-fourths" (which is the same as "one and one-fourth")
• $\frac{8}{3}$ = "eight-thirds" (which is the same as "two and two-thirds")
• $\frac{13}{5}$ = "thirteen-fifths" (which is the same as "two and three-fifths")

Clarity in Communication: Sometimes word forms make fractions easier to understand in conversation. Saying "three-fourths of the students" might be clearer than saying "$\frac{3}{4}$ of the students" when speaking aloud.

Mathematical Precision: Using precise vocabulary helps you think more clearly about what fractions represent. When you say "four-fifths," you're explicitly stating that you have 4 pieces, each of which is a fifth-sized unit.

Foundation for Algebra: Learning that fractions are single numbers (not "1 over 2" but "one-half") prepares you for more advanced mathematics where this understanding becomes crucial.

Some students read $\frac{3}{4}$ as "3 over 4" instead of "three-fourths." While "3 over 4" isn't wrong, it doesn't emphasize that this represents a single number. Saying "three-fourths" helps you remember that $\frac{3}{4}$ is one specific amount.

Another mistake is thinking that fractions always represent "part of one whole." Fractions like $\frac{7}{4}$ represent more than one whole, and fractions on number lines or in sets might not refer to traditional "wholes" at all.

When you use different forms, always connect them back to what the fraction actually represents:

• $\frac{2}{6}$ (standard) = "two-sixths" (word) = "2 sixths" (numeral-word)
• All three forms describe the same amount: 2 pieces, each piece being a sixth of the whole
• You can visualize this as 2 shaded sections in a shape divided into 6 equal parts

In daily life, you might encounter fractions in different forms:

• Recipes: "Add three-fourths cup of flour" (word form)
• Measurements: "The board is $\frac{7}{8}$ inches thick" (standard form)
• Time: "We spent 2 thirds of the afternoon playing" (numeral-word form)

Being fluent in all forms helps you understand and communicate in various situations.

To become comfortable with all three forms:

1. Practice converting between forms regularly
2. Read fractions aloud using word form
3. Write word problems using different forms
4. Connect each form to visual representations
5. Explain what each form means in your own words

Remember, regardless of which form you use, you're always talking about the same mathematical concept—a number that represents a specific quantity that can be less than, equal to, or greater than one whole.

Comparing fractions means figuring out which fraction is larger, which is smaller, or if they're equal. The strategy you use depends on what the fractions have in common. Let's explore two powerful comparison strategies!

When fractions have the same denominator, you're working with pieces of the same size. This makes comparison straightforward—just look at how many pieces you have!

For example, compare $\frac{3}{8}$ and $\frac{5}{8}$:

• Both fractions use eighths (pieces of size $\frac{1}{8}$)
• $\frac{3}{8}$ means you have 3 eighth-sized pieces
• $\frac{5}{8}$ means you have 5 eighth-sized pieces
• Since 5 pieces is more than 3 pieces, $\frac{5}{8} > \frac{3}{8}$

Real-World Example: Imagine two identical pizza pies, each cut into 6 equal slices 🍕. If Amy eats $\frac{2}{6}$ of her pizza and Ben eats $\frac{4}{6}$ of his pizza, who ate more? Since both pizzas are the same size and cut the same way, Ben ate more because 4 slices is more than 2 slices.

When fractions have the same numerator, you have the same number of pieces, but the pieces are different sizes. The fraction with the smaller denominator has larger pieces!

For example, compare $\frac{2}{3}$ and $\frac{2}{5}$:

• Both fractions represent 2 pieces
• $\frac{2}{3}$ means 2 pieces where the whole was divided into 3 parts
• $\frac{2}{5}$ means 2 pieces where the whole was divided into 5 parts
• Thirds are larger than fifths, so $\frac{2}{3} > \frac{2}{5}$

Think About It: If you have 2 slices of pizza, would you rather they come from a pizza cut into 3 pieces or a pizza cut into 5 pieces? The pizza cut into 3 pieces gives you bigger slices! 🍕

Number lines are incredibly helpful for comparing fractions because they show fractions as positions rather than just symbols.

Creating a Number Line: To compare fractions like $\frac{1}{4}$, $\frac{2}{4}$, and $\frac{3}{4}$:

1. Draw a line from 0 to 1
2. Divide the space into 4 equal parts (since the denominator is 4)
3. Mark $\frac{1}{4}$, $\frac{2}{4}$, and $\frac{3}{4}$ at their respective positions
4. The fraction farthest to the right is the largest

Reading the Order: On a number line, fractions increase from left to right, just like whole numbers. This visual makes it clear that $\frac{1}{4} < \frac{2}{4} < \frac{3}{4}$.

Rulers work exactly like number lines for fractions! When you measure something as $\frac{7}{8}$ inch, you're finding its position on a ruler divided into eighth-inch markings. This real-world connection helps you understand that fractions represent actual positions and distances.

Comparison strategies work for fractions greater than one too:

Same Denominator Example: Compare $\frac{7}{4}$ and $\frac{9}{4}$

• Both use fourths as the unit
• 9 fourths is more than 7 fourths
• So $\frac{9}{4} > \frac{7}{4}$

Same Numerator Example: Compare $\frac{5}{3}$ and $\frac{5}{6}$

• Both represent 5 pieces
• Thirds are larger pieces than sixths
• So $\frac{5}{3} > \frac{5}{6}$

Area Models: Use rectangles or circles divided into equal parts. Make sure both shapes are the same size to compare fairly. Shade the parts representing each fraction, then compare the shaded amounts.

Fraction Strips: These are rectangular strips divided into different fractional parts. You can line up strips to compare fractions visually. For example, place a $\frac{1}{3}$ strip next to a $\frac{1}{4}$ strip to see which is longer.

Set Models: Use groups of objects like counters or blocks. If comparing $\frac{2}{5}$ and $\frac{3}{5}$ of a set of 10 objects, you'd compare groups of 4 objects versus groups of 6 objects.

"Bigger denominator means bigger fraction": This is only true when numerators are the same. $\frac{1}{8}$ is actually smaller than $\frac{1}{4}$ because when you divide something into more pieces, each piece gets smaller.

"You can't compare different denominators": While it's true that you need special strategies (which you'll learn in Grade 4), you can compare fractions with the same numerator by reasoning about piece sizes.

As you practice comparing fractions, you develop fraction number sense—an intuitive understanding of fraction sizes. This helps you:

• Estimate whether answers are reasonable
• Make quick mental comparisons
• Understand fraction relationships
• Connect fractions to real-world quantities

To strengthen your comparison skills:

1. Use multiple visual representations for each comparison
2. Explain your reasoning aloud or in writing
3. Connect comparisons to real-world situations
4. Practice with number lines of different scales
5. Check your work using different methods

Remember, the goal isn't just to get the right answer—it's to understand why one fraction is larger or smaller than another. This understanding will serve you well as you encounter more complex fraction work in future grades!

One of the most amazing discoveries in mathematics is that different fractions can represent exactly the same amount! These are called equivalent fractions, and they're everywhere once you know how to spot them. Learning to identify and explain equivalent fractions helps you understand that the same quantity can be described in multiple ways.

Equivalent fractions represent the same amount or same position on a number line, even though they're written with different numbers. For example:

• $\frac{1}{2}$ and $\frac{2}{4}$ are equivalent
• $\frac{3}{6}$ and $\frac{1}{2}$ are equivalent
• $\frac{2}{3}$ and $\frac{4}{6}$ are equivalent

Think of it like this: if you and your friend each have identical candy bars, and you break yours into 2 equal pieces while your friend breaks theirs into 4 equal pieces, eating 1 of your pieces gives you the same amount of candy as your friend eating 2 of their pieces! 🍫

Area Models are perfect for showing equivalent fractions:

Imagine two identical rectangles. Divide the first rectangle into 2 equal parts and shade 1 part (showing $\frac{1}{2}$). Divide the second rectangle into 4 equal parts and shade 2 parts (showing $\frac{2}{4}$). You'll see that exactly the same amount is shaded in both rectangles!

This visual proof shows why $\frac{1}{2} = \frac{2}{4}$—they cover the same area of the same-sized whole.

Circle Models work similarly. Draw two identical circles. Divide one into 3 equal sections and shade 2 sections ($\frac{2}{3}$). Divide the other into 6 equal sections and shade 4 sections ($\frac{4}{6}$). The shaded amounts will be identical!

Number lines provide the most convincing evidence for equivalent fractions because equivalent fractions land on exactly the same point.

To test if $\frac{3}{4}$ and $\frac{6}{8}$ are equivalent:

1. Create one number line divided into fourths
2. Create another number line (same length) divided into eighths
3. Mark $\frac{3}{4}$ on the first line and $\frac{6}{8}$ on the second line
4. If they align perfectly when the number lines are placed one above the other, the fractions are equivalent!

For fractions to be equivalent, they must refer to the same-sized whole. This is crucial!

Correct Comparison: $\frac{1}{2}$ of a large pizza 🍕 equals $\frac{2}{4}$ of the same large pizza.

Incorrect Comparison: $\frac{1}{2}$ of a large pizza does NOT equal $\frac{2}{4}$ of a small pizza.

When using visual models or real objects, always ensure you're comparing fractions of identical wholes.

It's not enough to just identify equivalent fractions—you need to explain why they're equivalent. Here are thinking strategies:

Doubling Strategy: Notice that in $\frac{1}{2} = \frac{2}{4}$, both the numerator and denominator of $\frac{1}{2}$ were doubled to get $\frac{2}{4}$. When you double the number of pieces (denominator) and double how many you take (numerator), you get the same amount.

Halving Strategy: In $\frac{4}{6} = \frac{2}{3}$, both the numerator and denominator of $\frac{4}{6}$ were divided by 2 to get $\frac{2}{3}$. This works because you're taking half as many pieces from a whole that's been divided into half as many parts.

Visual Reasoning: "I can see that $\frac{3}{6}$ and $\frac{1}{2}$ are equivalent because when I draw both fractions using the same-sized rectangle, exactly the same amount is shaded."

Equivalent fractions appear constantly in everyday situations:

Cooking: A recipe calling for $\frac{1}{2}$ cup of milk is the same as $\frac{2}{4}$ cup or $\frac{4}{8}$ cup—all represent the same amount!

Time: $\frac{1}{2}$ hour equals $\frac{30}{60}$ minutes (30 minutes out of 60 minutes in an hour).

Money: $\frac{1}{4}$ of a dollar equals $\frac{25}{100}$ of a dollar (25 cents out of 100 cents).

In Grade 3, your job is to identify equivalent fractions and explain why they're equivalent, not to create or generate them. You might be given pairs like $\frac{2}{6}$ and $\frac{1}{3}$ and asked:

• Are these fractions equivalent?
• How do you know?
• Show your reasoning using a visual model or number line.

As you work with equivalent fractions, you'll start noticing patterns:

• $\frac{1}{2} = \frac{2}{4} = \frac{3}{6} = \frac{4}{8}$
• $\frac{1}{3} = \frac{2}{6} = \frac{4}{12}$
• $\frac{2}{3} = \frac{4}{6} = \frac{6}{9} = \frac{8}{12}$

These patterns will become important in Grade 4 when you learn systematic methods for generating equivalent fractions.

Fraction Manipulatives: Physical tools like fraction circles, strips, or tiles let you physically overlay fractions to check for equivalence.

Graph Paper: Draw area models using grid squares to ensure precision and easy comparison.

Multiple Representations: Always check equivalence using at least two different methods (like area models AND number lines) to confirm your conclusion.

When explaining equivalent fractions, use precise mathematical language:

• "These fractions are equivalent because they represent the same amount."
• "I can see they're equivalent by comparing their positions on the number line."
• "The visual models show the same area is shaded, proving they're equal."
• "Both fractions refer to the same-sized whole, and the shaded portions match exactly."

This practice in mathematical reasoning and communication prepares you for more advanced fraction work and helps you think more clearly about mathematical relationships.