Morph
Change one step at a time toward the chosen form; every step must work.
HEAD, heal, teal, tell, tall, TAIL.
Seen in M. C. Escher, Metamorphosis II, woodcut, November 1939 to March 1940, 19.2 by 389.5 cm
Try it on your work
Build a small tower of ten blocks that stands. Move one block at a time toward a chosen shape, an arch, say; the structure must stand after every move. Stop when the shape is reached.
Turn one four-letter word into another, changing one letter at a time, every step a real word. Stop at the target word.
A group changes its regular meeting toward a new format over five meetings, one change each time, and every meeting must still run. Stop at the fifth.
How it has been used
Start from a version that works and change it in small steps toward a form chosen at the start, keeping it working at every step: the word ladder, the tiling that turns from squares into birds, the layout moved one element at a time from the old grid to the new. The move forbids a broken step: if a step does not work, it is not taken.
Where it leads
Grouped under Let it respond to what happens