OpenStem

@openstem · Joined Jul 2026

7420 public items8 groups

Note~203 words · 1 min

x on both sides Two-step equations keep x on one side. Multi-step ones often don't. Distribute, then combine, then solve A number outside brackets multiplies EVERY term inside. The reliable order for any multi-step equation: distribute, com

Mathematics

Mathematics · L2 · Multi-Step Equations & Inequalities

@openstem

Note~218 words · 1 min

Slope is a rate, not just a steepness It answers: when x goes up by one, what happens to y? Reading slope from a table No graph needed. Watch what the output does each time the input steps up by one. What the sign tells you Drag m below and

Mathematics

Mathematics · L2 · Slope & Rate of Change

@openstem

Note~229 words · 1 min

Similar: same shape, different size Two figures are similar when every pair of corresponding angles is equal AND every pair of corresponding sides is in the same ratio. That shared ratio is the scale factor. What the scale factor does Above

Mathematics

Mathematics · L2 · Scale Drawings & Similar Figures

@openstem

Note~289 words · 1 min

Unfold it, then add up the pieces Surface area is the total area of every outside face: how much material would wrap it completely. Imagine cutting along the edges and flattening the solid into a net, then add every piece. Rectangular prism

Mathematics

Mathematics · L2 · Surface Area of Prisms & Pyramids

@openstem

Note~227 words · 1 min

Two ways to think about chance Theoretical: a fair die has one favourable face out of six equally likely ones, so 1/6, without touching a die. Experimental: roll it 60 times, get nine 3s, and the measured probability was 9/60 = 0.15. The La

Mathematics

Mathematics · L2 · Probability: Experimental vs Theoretical

@openstem

Note~309 words · 2 min

Histograms group numbers into bins A histogram sorts numeric data into equal-width ranges called bins and draws a bar for each. Because each bin starts exactly where the last one ends, the bars touch. Sort 11 test scores into bins of width

Mathematics

Mathematics · L2 · Histograms & Box Plots

@openstem

Note~255 words · 1 min

Rational: it can be written as a fraction That includes whole numbers (5 = 5/1), ordinary fractions (3/4), and negatives (−2/3). In decimal form a rational number always does one of exactly two things: Irrational: it can't An irrational num

Mathematics

Mathematics · L2 · Rational vs Irrational Numbers

@openstem

Note~254 words · 1 min

Build the line from a table No guessing needed. Pick x-values, solve for y, plot the pairs. Say the equation is y = 2x − 1: Or skip the table: use the intercepts Worked on 2x + 3y = 12: Two points, one straight edge, done. Two forms, same l

Mathematics

Mathematics · L2 · Graphing Linear Equations

@openstem

Note~116 words · 1 min

Sharing equally A fraction shows a part of a whole thing. Whenever you share something so everyone gets the same amount, you're using fractions. Cut a pizza into 2 equal pieces and eat one, and you ate half the pizza. The pieces have to be

Mathematics

Mathematics · L1 · Half and Quarter: Your First Fractions

@openstem

Note~283 words · 1 min

Turning a solved inequality into a picture Once you have something like x > 3 or x ≤ −2, the graph has two parts: a circle at the boundary number, and shading showing which other numbers are solutions. Open circle or closed? The circle answ

Mathematics

Mathematics · L2 · Graphing Inequalities on a Number Line

@openstem

Note~215 words · 1 min

One skill, a whole shopping trip Discounts, tax, tips and markup all start identically: find the percent of the price. Then you either add it or subtract it. Discount and tax, side by side Tips without a calculator Find 10% by moving the de

Mathematics

Mathematics · L2 · Percent Applications: Discount, Tax & Tip

@openstem

Note~283 words · 1 min

Rigid means the size never changes A transformation moves a figure from its starting position (the pre-image) to a new one (the image). Translations, reflections and rotations are all rigid: position and orientation change, size and shape n

Mathematics

Mathematics · L2 · Transformations: Translations, Reflections & Rotations

@openstem

Note~111 words · 1 min

Pictures instead of numbers A pictograph shows data using pictures, and each picture stands for a number. Imagine your class voted for a favourite fruit: apples 🍎🍎🍎, bananas 🍌🍌, grapes 🍇🍇🍇🍇. If each picture is 1 vote, apples got 3, bananas

Mathematics

Mathematics · L1 · Reading a Pictograph

@openstem

Note~226 words · 1 min

Putting groups together Some stories ask how many there are altogether. Watch for the words altogether, in total, or now. Maya has 4 apples and picks 3 more. To find how many she has now, add: 4 + 3 = 7. Taking some away Other stories ask h

Mathematics

Mathematics · L1 · Addition & Subtraction Stories

@openstem

Note~206 words · 1 min

Counting in jumps Skip counting means counting forward in equal jumps instead of one at a time. It's a fast way to count things that come in groups, like pairs of shoes or fingers on hands. Odd and even Skip counting by 2s from 2 lists only

Mathematics

Mathematics · L1 · Skip Counting & Patterns

@openstem

Note~215 words · 1 min

Comparing without numbers Line up one end of each object and put them side by side. Whichever sticks out further is longer. No numbers needed at all. Measuring with everyday objects Before rulers, people measured with whatever they had: pap

Mathematics

Mathematics · L1 · Measuring Length & Weight

@openstem

Note~216 words · 1 min

Two hands, two jobs At half past, the short hand sits BETWEEN two numbers, not on one. That's a good clue you've read it right. Days of the week Seven days, always in the same order, and after Sunday it starts again at Monday. Months of the

Mathematics

Mathematics · L1 · Telling Time & Calendars

@openstem

Note~245 words · 1 min

Solid shapes take up space 3D shapes aren't flat on paper. They take up room, and they're everywhere once you look. Faces, edges and corners Symmetry: folding in half A shape has line symmetry if you can fold it exactly in half and both sid

Mathematics

Mathematics · L1 · 3D Shapes & Symmetry

@openstem

Note~173 words · 1 min

Sorting by one rule Sorting means putting things into groups by a rule. Pick a rule, like "is it red?", and everything that matches goes in one pile. Draw one circle and write the rule above it. Only things that follow the rule go inside. S

Mathematics

Mathematics · L1 · Sorting with Venn Diagrams

@openstem

Note~189 words · 1 min

Four words for how likely Some things always happen. Some never do. Most are somewhere in between, and four words cover the whole range. Sorting everyday events Putting events in order Start with the ones that can never happen, then the one

Mathematics

Mathematics · L1 · Likely, Unlikely, Certain

@openstem

Note~233 words · 1 min

Adding up what you have Add every coin and bill one at a time. The order doesn't matter; the total comes out the same. Getting change Pay more than something costs and the shopkeeper gives back the difference. That's your change, and there

Mathematics

Mathematics · L1 · Money & Making Change

@openstem

Note~217 words · 1 min

A shortcut for adding the same number 3 groups of 4 counters is 4 + 4 + 4, or just 3 × 4. Both give 12. The bigger the numbers, the more it saves you. Adding 8 groups of 6 one at a time takes a while; 8 × 6 is instant. Arrays: rows and colu

Mathematics

Mathematics · L1 · Simple Multiplication

@openstem

Note~221 words · 1 min

Splitting into equal parts You have 12 cookies and 4 friends. Hand them out one at a time going round the group until they're gone, and everyone ends up with 3. That's 12 ÷ 4 = 3. The ÷ symbol means divide, or share equally. Two questions,

Mathematics

Mathematics · L1 · Simple Division

@openstem

Note~196 words · 1 min

Three symbols, three answers Compare two numbers and only three things can be true: one is bigger, one is smaller, or they're the same. Comparing two-digit numbers Compare 52 and 58: both have 5 tens, so that's a tie. 58 has 8 ones and 52 o

Mathematics

Mathematics · L1 · Comparing & Ordering Numbers

@openstem

Note~239 words · 1 min

Words that say where In front of and behind In a line at school, the person in front of you is nearer the front and the person behind is nearer the back. One thing can be described several ways at once. A dog can be behind a tree, hidden on

Mathematics

Mathematics · L1 · Position & Direction Words

@openstem

Note~272 words · 1 min

Pairs that make a target A number bond is two numbers that add to make a target. Learning the bonds to 10 and 20 by heart makes everything else faster, because you stop counting and start remembering. Each bond works both ways round: 7 + 3

Mathematics

Mathematics · L1 · Number Bonds to 10 and 20

@openstem

Note~201 words · 1 min

From tally to bar Once you've counted a group, that count IS the bar height. Nothing more complicated than that. Most and least You don't even need the numbers. Your eyes can find the tallest and shortest bars straight away, which is exactl

Mathematics

Mathematics · L1 · Making & Reading Bar Graphs

@openstem

Note~201 words · 1 min

Four relationships worth knowing on sight Spot the relationship and you can find a missing angle without measuring anything. Complementary and supplementary Vertical angles Two straight lines crossing make four angles in two matching pairs.

Mathematics

Mathematics · L2 · Angle Relationships

@openstem

Note~173 words · 1 min

The parts Circumference: the distance around Divide any circle's circumference by its diameter and you always get π, about 3.14. That's where both formulas come from. Area: the space inside One circle, all three quantities

Mathematics

Mathematics · L2 · Circles: Circumference & Area

@openstem

Note~241 words · 1 min

One rule, shown several times A function table pairs inputs with outputs. Every pair follows the same hidden rule. Hunting for the rule Using the rule Writing a rule from a real pattern If 1 pencil costs $2, 2 cost $4, and 3 cost $6, the ru

Mathematics

Mathematics · L2 · Function Tables & Input-Output Rules

@openstem