HS Physics v2 demo 3, as the TimeBack player shows it

What this is. The motor effect and momentum topics rendered through David Babagbale's mimic of the TimeBack player: one column of cards, revealed one at a time by Continue, with every question a gate the student must answer correctly to move on.

A lesson page: the video in the first card → its one question (a gate) → one worked-examples card whose steps are click-to-reveal bars (Continue stays off until every step is opened) → the quiz, one gated checkpoint per item.

What the mimic cannot show. On the real platform the video is its own activity before the lesson; here it sits in the first card. A typed-word item appears as a practice card with its answer printed (the player types it). Options shuffle on every load. Nothing here is changed from demo 3; it is the same content in the player's shape.

Tip: add #auto=end to a page's address to see it fully revealed and answered; #auto=wrong shows the red retry state.