Grade 9 · Math

Grade 9 math

Grade 9 is the first year of high-school math, and algebra takes over: equations with several steps, lines on a graph, exponent laws. Here is what it covers, where students usually get stuck, and one way to help.

What your teen learns this year

Curricula organize grade 9 differently, but most cover the same core:

  • Equations. Solving multi-step equations and inequalities, including ones with brackets and fractions.
  • Linear relations. Slope, intercepts, and the equation of a line from a graph, a table or a story.
  • Exponents and polynomials. Exponent laws, and adding, subtracting and multiplying simple polynomials.
  • Geometry and measurement. The Pythagorean theorem, area, surface area and volume, and angle properties.
  • Data and money. Analysing data and lines of best fit; Ontario's course adds financial literacy and coding.

Ontario's grade 9 math is one course for everyone (MTH1W). In much of the US, grade 9 is Algebra 1, and the western provinces split into course paths from grade 10.

Where kids usually get stuck

  1. 1Undoing steps in the wrong order. In 3(x − 4) + 2 = 20, dividing by 3 first means the 2 has to be divided too, and fractions appear. Undo the + 2 first.
  2. 2Forgetting to flip the inequality. Dividing both sides of −2x > 6 by −2 turns the sign around: x < −3, not x > −3.
  3. 3Losing the minus sign on a bracket. −(x − 4) is −x + 4. The minus applies to everything inside.

One of Pip's tricks

Undo from the outside in

Use it when solving a multi-step equation like 3(x − 4) + 2 = 20.

  1. List what was done to x, in order: subtract 4, times 3, add 2.
  2. Undo those steps in reverse order (subtract 2, divide by 3, add 4), doing the same to both sides each time.
  3. Put your answer back into the original equation to check it.

Watch it work. 3(x − 4) + 2 = 20. Undo the + 2: 3(x − 4) = 18. Undo the × 3: x − 4 = 6. Undo the − 4: x = 10. Check: 3 × (10 − 4) + 2 = 20.

Why it works: an equation is built from the inside out, so you unwrap it from the outside in, like taking off a coat before a shirt.

Try three

Have a go, then tap to see the answer.

  1. 1.Solve: 2(x + 5) − 3 = 17

    Show the answer

    x = 5. Add 3: 2(x + 5) = 20. Divide by 2: x + 5 = 10. Subtract 5: x = 5.

  2. 2.Solve: 4x − 7 = 2x + 9

    Show the answer

    x = 8. Subtract 2x from both sides: 2x − 7 = 9. Add 7: 2x = 16. Divide by 2: x = 8.

  3. 3.Solve: −2x > 6

    Show the answer

    x < −3. Dividing both sides by −2 gives −3, and dividing by a negative flips the sign.

How Sparkpip fits in

Pip, Sparkpip's tutor, works through problems like these with your teen one small step at a time, using methods like the one above.

Start freeSee how it works

Your curriculum

Sparkpip is built on the grade 9 math curriculum for your province or state. The official pages:

Also: Grade 8 math · Grade 10 math · Grade 9 science · Grade 9 English