Although this website isn't in English, it does have some great letter printables!
Free and inexpensive, fully planned Montessori units compiled by a Montessori teacher
Visited Archetypes.com and took the Quiz, which resulted in three archetypes. The primary archetype (at 36%) was the Intellectual.
Here's a simple game where students move around the board adding and subtracting blocks while trying to build the tallest tower.
Letter recognition uppercase and lowercase
Personal Space - Visual Story for Kids with Autism by Kmintz
Jean Piaget (1896-1980): Developmental and child psychologist best known for his four-stage theory of cognitive development