What does it mean that capture what surprises you?

Surprise indicates a gap between your model and reality — always worth noting.

Example: You walk into a one-on-one expecting your usually disengaged report to ask about deadlines. Instead, she pitches a restructured workflow that solves a problem you hadn't even named yet. Your stomach does a small flip — that's surprise. If you don't write it down, you'll remember she 'had a good idea' but lose the specific gap it revealed: your model of her capabilities was wrong, and your model of the problem space was incomplete. Both of those gaps are more valuable than the idea itself.

Try this: For the next 48 hours, carry a capture tool and tag every surprise with the prefix 'S:' — even tiny ones. 'S: The coffee shop I assumed closed on Mondays was open.' 'S: That API call returned in 20ms when I expected 200ms.' 'S: My partner remembered a detail from a conversation I forgot we had.' At the end of 48 hours, review the list. For each entry, write one sentence answering: 'What did I apparently believe that turned out to be wrong?' You now have a map of where your mental models are miscalibrated.