Play Sonar detective together on one device, or let the computer make a mystery. Hide a secret underwater scene, aim the sonar, send pulses, and use the echoes to mark your own map. Reveal the hidden scene and compare your guesses. Points reward position and motion clues; similar echoes do not uniquely identify an object. The new “Seeing the unseen” opening brings waves, atoms and light together through photographs and moving diagrams. Follow the short story with English or Chinese captions, pause or skip whenever you like, or explore the full 27-slide presentation. The story and activities work offline.

Explore the new Wave Garden: draw walls, place sources and try wave and light scenes. Hide the controls for a clear view and bring them back when needed. An optional sonar activity introduces echo timing and frequency. Island maps now use less space, with a compact route back to your last experiment. This update also improves small-screen text, touch controls and saved-apparatus recovery.