Our stereognostic sense is about being able to recognize items through our sense of touch only, no visual sense involved. We use it in our daily life anytime we are going through a bag, a purse, a pocket looking for our keys without seeing or have any visual of those keys. Montessori provides tools to practice and refine this skill.
In Montessori education, we use the stereognostic exercises and games in the sensorial area of the classroom. A lot of the sensorial material used by the children can also be used stereognostically or to use simpler words, with a blindfold or by closing our eyes (no peeking!!!). The child starts using the pink tower, for example, which is made of 10 cubes going from bigger to smaller. She would first be introduced to building the tower by the Montessori guide and once the child seems more comfortable, the guide would introduce extensions and games, some of them can involved wearing a blindfold so the child has to recognize the size of a cube by using her touch only. It makes the material more interesting in a different manner and the challenge is usually really well received by the children. Some of those stereognostic exercises can involve a group activity as well.
Our favourite stereognostic activity here at home is the Mystery bag. A hamstring bag in which are hidden 10 to 12 objects. Those objects are usually familiar to the young child living in a Montessori home or going to a Montessori school. The children have to put their hand(s) in the Mystery bag without looking at what is inside of it. With their hands, the most wonderful tool of the child, they feel around until they find an object, touch it with both hands if needed and say what they think it is. Only then, they can take the object out of the bag for verification.
The objects placed in the bag should be familiar to the child, enough that she could recognize them and name them. We usually do not put toys as they can take away the focus of the sensorial experience and it also distracts the child from continuing his activity.
This is also a language activity as you name the objects and you can have several bags or rotate objects to give more language to the child as she grows. Some people use the mystery bag for mini geometric solids as well once the children have been introduced to them. It can also be used as a matching game if you place 5 pairs of objects in the bag (2 buttons, 2 feathers etc).
Try it at home with what you have if you are interested in playing this with your child. Here, at Chez Mahé, we cannot wait for our baby girl to be old enough to play with it so we can make her a Mystery bag !