Create a friendly educational visual for a modern classroom lesson about human joints. An adult teacher points to a large simplified skeleton model and colorful joint diagrams on a clean board with only abstract unreadable marks, while diverse students are seen from behind at desks. Use a landscape 4:3 composition, bright natural light, clear pedagogical layout, warm approachable style, realistic 3D illustration mixed with classroom photography, no medical gore, no readable text, no logos, no watermark.