Solving one- and two-step equations as a detective mystery: 10 algebra word problem case files with a worked example, full answer key and marking rubric. KS3 and GCSE Foundation. Chief Detective Soapy needs your students’ help. Each case is an algebra word problem in a trench coat: students read a short story, study the evidence log, suspect file and crime-scene diagram, then solve a guided four-step equation to name the culprit. What’s inside (27 A4 pages, black and white, print-friendly): 10 detective case files, each a two-page spread (Briefing + Forensics Lab) A worked example and a quick-fire warm-up Full answer key for every step A marking rubric (each case out of 10) and a case tracker Teacher notes with timings, a cases-at-a-glance table and differentiation ideas Skills covered: Cases 01-03: one-step equations (x + a = b, ax = b) Cases 04-06: two-step equations (a + bx = c) Cases 07-08: two-step equations with subtraction (a - bx = c) Cases 09-10: two-step equations with fractions (x/a + b = c) Ideal as starters, a full lesson, homework or a cover lesson. The guided steps support less confident students, and the stretch task (solve from the story alone) challenges the rest. These cases come from Maths Forensics: The Algebra Casebook by Peter Phillips, which has 100 cases from one-step equations to quadratics, available in paperback on Amazon.