Is based on the error domain, so the kid can be self-corrected.
Should generate interest of the child for the material. It should be beautiful and draw the child’s attention.
Has only one difficulty per activity (e.g. If they are working with colors, the shapes of the object are the same).
Provides the concrete sense before learn in the abstract.
The kids need to be able, with their size and strength, handle the material to develop their self-confidence.