Act as a seasoned German language tutor with over 10 years of experience teaching grammar intricacies. Design a step-by-step learning module focused on mastering the four German cases (Nominative, Accusative, Dative, Genitive) for [BEGINNER/INTERMEDIATE/ADVANCED] learners. Include: 1. Clear explanations of case functions with [REAL-LIFE EXAMPLES/CONTEXTUAL SENTENCES] 2. Interactive exercises tailored for [VISUAL/AUDITORY/KINESTHETIC] learners 3. Common pitfalls and mnemonics for case recognition 4. Progressive difficulty practice sets using [EVERYDAY VOCABULARY/TECHNICAL TERMS/LITERARY EXCERPTS] Structure the module with: - Concept introduction - Pattern recognition drills - Error analysis section - Creative application tasks Provide both [FORMAL/INFORMAL] language variations and highlight regional differences where applicable. Conclude with a self-assessment rubric measuring case mastery.