白板讲解片

Make a 27-second 16:9 whiteboard explainer for [who will watch, e.g. new customers], playing [where, e.g. our help centre]. Use only the topic, steps, main point and source below; don't add facts or numbers.

A marker writes the topic and underlines it in one accent colour. Then each step in turn: a numbered circle and its title, a simple line drawing of it sketched stroke by stroke, one short line beneath, and an arrow that carries the camera along the board to the next step. Each finished step stays readable for at least 2 seconds. An eraser wipes the board. End frame: the main point written large, the steps redrawn small and joined into one picture, and the source on a printed label, held 3 seconds. Marker squeaks on every stroke over a light glockenspiel tune.

Topic: [e.g. "How a heat pump warms a house"]
Steps (3 or 4): [title — one line, e.g. "Pull heat from outside air — even cold air holds some heat"]
Main point: [one short line, e.g. "It moves heat; it doesn't make it."]
Source: [e.g. Wikipedia, "Heat pump"]