Within ACL 3.2, back and forth movements create the concrete concept of a line after it is visible. The actions rub over the same space, which can be seen as a wide line.
Different objects on different surfaces can create a line:
- The objects can include sticks, crayons, pencils, pens, and brushes.
- The surfaces can include dirt, sand, paper, and walls.
Familiar objects that are bilateral and can be moved back and forth include sanders and rolling pins.