Unit 24 · Inequalities
Inequalities
Mathematics · Grade 7
What You Will Be Able To Do
↔️Read and write the four inequality symbols correctly
📏Show an answer on a number line, with the right kind of circle
🔄Know exactly when the sign flips, and prove why
✅Check an answer with two numbers, one allowed and one not
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Solving an inequality uses exactly the same moves as solving an equation, with a single exception: multiplying or dividing by a negative number flips the sign round.
Presenter notes: Open with the question left hanging at the end of last lesson. Write 3 is less than 5 on the board and ask whether it is true, which everybody agrees it is. Then multiply both sides by minus one in front of them and ask whether the new statement is still true. It is not, and that single demonstration is the reason this lesson exists.