Mathematics · Grades 6–9
Equations, expressions and equivalent steps · Revision sheet
Preserve equality and check a solution in the original equation.
Learn the idea
Expression or equation
An expression represents a value; an equation asserts equality between two expressions.
Balance
Applying the same valid operation to both sides preserves an equation. Division by zero is never valid.
Distribute
a(b + c) = ab + ac. The multiplier acts on every term inside the brackets.
Check
Substitute a proposed solution into the original equation, not just a rearranged line.
Explain without looking
- A student changes x + 4 = 9 into x = 13. Describe a valid next step instead.
- Explain why 2(x + 1) = 2x + 2 has no single unique solution over the real numbers.
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.