IB MYP 5 Mathematics | Criterion B Investigation — The Modulus Function f(x) = |x| | Answer Key & Markscheme Included

A complete, print-ready Criterion B investigation that takes students from first observations to a fully justified generalization — exploring how the slope of the line g(x) = mx + 1 determines the number of solutions to |x| = mx + 1. Designed to assess Criterion B (Investigating Patterns) against the IB MYP rubric, with built-in scaffolding from Levels 1–2 through Levels 7–8.

Everything is ready to print and hand out. No prep, no calculus, GDC-friendly.

What's included

• 8-page student investigation (3 parts, scaffolded by achievement level)
• Full teacher markscheme: model answers, per-question mark allocation (30 marks total), and Criterion B level descriptors for every question
• Student answer key with complete reasoning for self-checking

How it's structured

• Part A (Levels 1–4): vertex, domain & range, symmetry, and reading intersections from given graphs
• Part B (Levels 5–6): forming a conjecture and solving |x| = mx + 1 algebraically by cases
• Part C (Levels 7–8): validity analysis, a full classification table for every value of m, and a slope-based geometric justification

Why teachers use it

• Maps directly to the MYP Criterion B descriptors — grade consistently and defensibly
• Genuinely tiered: every student has an entry point, and the strongest are pushed to a rigorous Level 7–8 proof
• Avoids calculus entirely — justifications use the definition of |x|, validity conditions, and slope reasoning

Details at a glance

• Level: Grade 9–10 / MYP Year 5
• Time: ~50–60 minutes
• Marks: 30
• Format: PDF (print-ready); GDC permitted

Perfect as a formative or summative Criterion B task, a revision activity, or an exemplar of what a well-structured investigation looks like.