Curriculum › Math ›Grade 6

Grade 6 Math · Level 3, Expressions, Equations & Inequalities

Model & Solve One-Step Equations

How the lesson starts: Model & Solve One-Step Equations

1. Farmer Tess's scale

   Good morning from the farmers' market! Farmer Tess has a balance scale. On one side, a mystery bag of x apples and 9 more apples. On the other side, 23 apples. The scale is perfectly level! How many apples hide in the bag?

2. Story to equation

   First, turn a story into an equation. A box had x cards. After adding 7, it has 20. Start with the box, x. Adding 7 makes x + 7. It now has 20, so x + 7 = 20. The equals sign is the level scale.

3. Undo the adding

   Back to x + 9 = 23. The bag got 9 added, so undo it: take 9 away. But take 9 from both sides, or the scale tips! x + 9 − 9 = 23 − 9. So x = 14. Check it: 14 + 9 = 23. Balanced!