An integral part of the Montessori experience is the sensorial material here is a short guide that 2.5 to 3 years olds can be introduced to and should be able to choose to work with independently.
Pink Tower: Lesson 1 and 2. and with matching cards.
Cylinder Block 1 and 2 and together.
Colour Box 1 and 2, sensorially and then 3 period lesson for names of colours.
Brown (broad) Stair
Texture boards, touch tablets and pairing touch tablets
Simple sorting and/or matching, for example hard/soft, colours, shapes and sizes.
Geometric Solids sensorially and Geometric Solids pairing.
Stereognostic bag (mystery bag)
There are explorations and extensions to these sensorial materials that children are welcome to experiment and develop.
This is a glimpse as to what the potential is, would you like to add more?