A 25-minute Algebra 1 lesson for grades 7-9 on solving two-step equations and checking solutions by substitution. Includes warm-up, worked example, guided practice, four independent questions, exit ticket and complete teacher answer key. Students apply the same operation to both sides and verify each answer in the original equation. Support and extension activities are included. Prepared by the Gauth team. Licensed under Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0).