Solution to Challenge 1

Method
1. Fold the square in half both ways and unfold.
2. Fold each edge to the centre line and unfold (quarters).
3. Repeat once more to reach eighths: an 8 by 8 grid.
4. Hold the sheet to a window and check that the lines are evenly spaced.

Common drift causes
- The corners did not meet exactly before the crease was pressed.
- The crease was started in the middle instead of at one edge.
- The paper shifted while being pressed.

Fix: re-fold from a cleaner centre crease, or use a ruler and bone folder.

Checkpoint: 64 equal squares and no line that wanders by more than a millimetre.