Two slits and a mystery.
We open with the double-slit experiment — not as math, but as theatre. Children watch how a single particle, somehow, goes through both slits at once. Then we let them sit with the discomfort.
‘So… the universe doesn't have to make sense?’ they ask. We say: ‘Not the way you expected. Welcome to the most interesting class you'll take this year.’
‘So the universe doesn't have to make sense?’ Welcome.

