Search & glossary

Every rule and concept in Grade 4, with its definition and a link to the lesson that teaches it. Search by term, by idea, or by lesson title.

Glossary (52)

A clock is a circle of turns: A full turn is $360^\circ$ .; Angles › Word Problems
Angles add: When a ray splits an angle into two parts, the parts add to the whole.; Angles › Adding and Splitting Angles
Around versus inside: Perimeter is the distance around a shape: add the lengths of all its sides.; Angles › Perimeter and Area on Grid Paper
Bars for categories: A bar graph shows how many are in each category: fruits, pets, days of the week.; Line Plots › Bar Graphs
Cut the pieces to one size: To add $\tfrac13 + \tfrac14$ , find a number both denominators divide into, here $12$ , and rewrite both fractions as twelfths.; Adding Fractions › Unlike Denominators
Factor or multiple?: Splitting a group into equal parts with none left over asks for a factor.; Factors and Multiples › Word Problems
Four partial products: With two two-digit numbers the area model has four pieces: tens $\times$ tens, tens $\times$ ones, ones $\times$ tens, ones $\times$ ones.; Multi-Digit Multiplication › Two-Digit by Two-Digit
Four steps: To make a line plot:; Line Plots › Making a Plot
Fractions on the axis: Measurements are often fractions ( $\tfrac14$ inch, $\tfrac12$ inch, $\tfrac34$ inch).; Line Plots › Reading Fraction Line Plots
In plain terms: Break each number into tens and ones, multiply every piece, then add the pieces up — that is the distributive property, $a(b+c) = ab + ac$ .; Multi-Digit Multiplication › In Plain Terms & More Examples
In plain terms: Share into equal groups as far as you can; whatever is left over is the remainder, and it is always smaller than the number you divided by.; Long Division › In Plain Terms & More Examples
In plain terms: A fraction is in lowest terms when the top and bottom share no common factor but $1$ .; Equivalent Fractions › In Plain Terms & More Examples
In plain terms: When the denominators already match, just add or subtract the top numbers — the piece size (the bottom) stays the same.; Adding Fractions › In Plain Terms & More Examples
In plain terms: Line up the decimal points so tenths sit under tenths and hundredths under hundredths, then add place by place.; Decimals to Hundredths › In Plain Terms & More Examples
In plain terms: A factor divides evenly with nothing left over; a multiple is what you get by counting up in steps of the number.; Factors and Multiples › In Plain Terms & More Examples
In plain terms: An angle measures how far something turns.; Angles › In Plain Terms & More Examples
In plain terms: Each dot is one measurement.; Line Plots › In Plain Terms & More Examples
Money is hundredths: A dollar is $100$ cents, so one cent is $\$0.01$ , one hundredth of a dollar.; Decimals to Hundredths › Word Problems
One point, many names: On a number line from $0$ to $1$ , a fraction is a point.; Equivalent Fractions › Fractions on a Number Line
One strip for each place: Split a three- or four-digit number into thousands, hundreds, tens and ones, multiply each part by the one-digit number, and add.; Multi-Digit Multiplication › Bigger Numbers Times One Digit
Pad with zeros: To compare $0.5$ and $0.35$ , write $0.50$ and $0.35$ — fifty hundredths beats thirty-five.; Decimals to Hundredths › Comparing and Rounding
Partial products, added as you go: The column method multiplies one place at a time, starting with the ones.; Multi-Digit Multiplication › The Standard Algorithm
Place by place: Ask how many times the divisor fits into the hundreds, then bring down the tens, then the ones.; Long Division › Dividing Three-Digit Numbers
Reading a proof: Do not read a proof the way you read a rule.; Multi-Digit Multiplication › Why It Works
Reading a proof: Do not read a proof the way you read a rule.; Long Division › Why It Works
Reading a proof: Do not read a proof the way you read a rule.; Equivalent Fractions › Why It Works
Reading a proof: Do not read a proof the way you read a rule.; Adding Fractions › Why It Works
Reading a proof: Do not read a proof the way you read a rule.; Decimals to Hundredths › Why It Works
Reading a proof: Do not read a proof the way you read a rule.; Factors and Multiples › Why It Works
Reading a proof: Do not read a proof the way you read a rule.; Angles › Why It Works
Reading a proof: Do not read a proof the way you read a rule.; Line Plots › Why It Works
Same amount, two ways to write it: A decimal is a fraction with $10$ or $100$ on the bottom: $0.1 = \dfrac{1}{10} = \dfrac{10}{100}$ , and $0.35 = \dfrac{35}{100}$ .; Decimals to Hundredths › Tenths and Hundredths as Fractions
Same bottom, then compare tops: To compare $\tfrac23$ and $\tfrac34$ , rewrite both with denominator $12$ : $\tfrac{8}{12}$ and $\tfrac{9}{12}$ .; Equivalent Fractions › Comparing Fractions
Same-size wholes: Fractions of different things cannot be compared.; Equivalent Fractions › Word Problems
Spotting a multiplication: A story needs multiplication when it has equal groups: rows with the same number of chairs, boxes with the same number of pencils.; Multi-Digit Multiplication › Word Problems
Take away easy groups: Division asks how many groups of the divisor fit.; Long Division › Partial Quotients
Test small primes: A number is prime if its only factors are $1$ and itself.; Factors and Multiples › Prime or Composite?
The Big Idea: Split each number into its places and multiply the parts, then add.; Multi-Digit Multiplication › The Area Model
The Big Idea: Divide as far as you can in whole groups.; Long Division › Sharing What Is Left
The Big Idea: A fraction is in lowest terms when the top and bottom share no factor except $1$ .; Equivalent Fractions › Lowest Terms
The Big Idea: You can only add pieces that are the same size.; Adding Fractions › Why Denominators Must Match
The Big Idea: The places keep dividing by ten past the decimal point: tenths, then hundredths.; Decimals to Hundredths › Place Value After the Point
The Big Idea: Factors come in pairs that multiply to the number, which is why you only have to test up to the square root — after that the pairs repeat.; Factors and Multiples › Factors in Pairs
The Big Idea: An angle measures a turn.; Angles › Naming Angles
The Big Idea: Each dot is one measurement.; Line Plots › Reading a Line Plot
The check: Always: $\text{divisor} \times \text{quotient} + \text{remainder} = \text{the original number}$ .; Long Division › Sharing What Is Left
The three names: Less than $90^\circ$ is acute.; Angles › Naming Angles
What the remainder means: After dividing, ask what the remainder is in the story.; Long Division › Word Problems
Where two skip-counts meet: Skip-count by each number.; Factors and Multiples › Common Multiples
Which operation?: In all, altogether and total put amounts together: add.; Adding Fractions › Word Problems
Whole parts and fraction parts: Add the wholes and the fractions separately, then regroup if the fraction part is $1$ or more.; Adding Fractions › Mixed Numbers
Zero in the middle: If a step gives $0$ , WRITE the $0$ in the quotient.; Long Division › Dividing Three-Digit Numbers