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15 guides

Grade 1 · Grade 2 · Grade 3 · Number and operations · Patterns and algebra

Doubling, Halving, Odd, and Even

Doubling makes two equal copies; halving reverses that action when a quantity can be split into two equal whole-number groups.

Skills: Double and halve whole-number quantities · Reason about odd and even numbers

Grade 2 · Grade 3 · Grade 4 · Measurement

Finding Elapsed Time

Treat time as a distance between two moments, using friendly jumps in hours and minutes instead of fragile clock arithmetic.

Skills: Solve elapsed-time problems

Grade 2 · Grade 3 · Grade 4 · Number and operations

Equal Groups, Multiplication, and Division

Use multiplication to combine equal groups and division to reverse the relationship by finding a group size or a number of groups.

Skills: Multiply equal groups · Divide equal groups

Grade 4 · Data and probability

Expected Value as a Long-Run Average

Expected value describes the average outcome over many repetitions, so it can be meaningful even when it is not a possible result of one trial.

Skills: Interpret a non-whole expected value

Grade 12 · Patterns and algebra · Calculus and analysis

Formula Notation and Self-Checking Grids

Translate each formula before calculating, then use repeated totals as checksums that can expose and locate a corrupted entry.

Skills: Evaluate advanced symbolic expressions · Use overlapping checks to locate an error

Grade 2 · Grade 3 · Grade 4 · Number and operations

Fractions as Equal Parts

A fraction names equal-sized parts of one whole; the denominator names the partition and the numerator counts selected parts.

Skills: Represent a fraction of a whole · Find one tenth of a quantity

Grade 1 · Grade 2 · Grade 3 · Number and operations · Patterns and algebra

How a Hundred Chart Is Organized

Use the chart's fixed row and column structure: horizontal moves change by 1, while vertical moves change by 10.

Skills: Use hundred-chart structure

Grade 2 · Grade 3 · Grade 4 · Number and operations

Planning a Multi-Step Word Problem

Turn a longer situation into a short chain of questions, keep track of what each number means, and check the final result against the story.

Skills: Add and subtract whole-number quantities · Solve a multi-step word problem

Kindergarten · Grade 1 · Grade 2 · Grade 3 · Number and operations · Geometry

Position, Direction, and Number Lines

Track an ordered position by fixing a direction, using equal steps, and distinguishing a location from the distance traveled to reach it.

Skills: Use number-line structure · Model relative positions

Grade 1 · Grade 2 · Grade 3 · Number and operations

Hundreds, Tens, and Ones

Understand a three-digit number as equivalent collections of hundreds, tens, and ones that can be regrouped without changing the total.

Skills: Compose and decompose whole numbers to 1,000

Grade 2 · Grade 3 · Grade 4 · Measurement · Geometry

Rectangle Area and Perimeter

Keep two measurements distinct: area counts square units covering the inside, while perimeter measures length around the boundary.

Skills: Find rectangle area by multiplication · Find rectangle perimeter

Grade 1 · Grade 2 · Grade 3 · Grade 4 · Patterns and algebra

Reasoning About Repeating Patterns

Find the smallest repeating unit, locate positions within the cycle, and count complete cycles before handling any leftover positions.

Skills: Identify a position in a repeating cycle · Count categories in a repeating pattern

Grade 2 · Grade 3 · Data and probability

Reading a Scaled Picture Graph

Use the graph key as a multiplication rule: each picture may represent several objects rather than just one.

Skills: Interpret a scaled picture graph

Kindergarten · Grade 1 · Number and operations

Counting, Comparing, and Making Small Numbers

Build early number sense by matching one count word to each object, recognizing the total, comparing collections, and composing a number from smaller parts.

Skills: Count and compare within 20 · Compose and decompose within 5

Grade 4 · Measurement · Geometry

Volume as Equal Layers of Cubes

Connect the volume formula to counting unit cubes: find cubes in one rectangular layer, then multiply by the number of equal layers.

Skills: Find rectangular-prism volume by multiplication