Create a practice problem set for {{topic}} aimed at {{target_audience}}. Use a {{tone}} tone. Focus on {{learning_focus}}. Include: Problem Set Overview, 3 Warm-Up Problems, 4 Intermediate Problems, 3 Challenge Problems, Self-Assessment Rubric, and Answer Key Summary. Each problem must be concrete and relatable. Keep under 1800 words. Use plain language. If a concept is too advanced, say CONCEPT_TOO_ADVANCED. Paste any relevant background information after these instructions before running.