The Mystery Bag is a Montessori work that falls under the "Sensorial" umbrella. It's usually presented to children between 3 and 6 years old, and it requires them to make a mental picture of the objects (which they cannot see) in the bag.
The big buzz word we learned to go with this work (and which I've never heard at any other time!): "stereognostic." That's the 3-dimensional sense you get of an object when you can touch it or even lift it, giving you a good idea of what the shape of it may be and maybe what it's made of.
It's VERY easy and basically FREE to do this work! As you can see in the photo above we just used a mat, random objects from around the house, and an opaque bag (this one is really pretty and has a drawstring at the neck, so it's harder for any little people to peek at what's inside!).
I stuck about a dozen random objects in the bag, all of which had different characteristics (how soft or hard, how cold or warm to the touch, how smooth or rough, how heavy or light, etc.). Before we started the game I displayed the items on the mat, let "Alleluia" feel each one, and I told her its name. The new twist: I used a lot of descriptive language. For instance, "This is small and not very heavy. It feels cold in my hands.... it's shaped like a circle......it's made of metal.....one side has bumps and ridges, but the other side just has a bump in the center." (this was a button) At 3, Alleluia is very chatty and eager to add words to her vocabulary.
After the intro, I stuffed everything back in the bag and invited her to put her hand in (with eyes closed). I told her to hold just one thing in her hand, describe it to me, and guess what it might be. I was surprised that she didn't open her eyes! Some kids would rather use a blindfold than keep their eyes closed, but she seemed to love this game. She really wasn't very good at guessing the objects, but she enjoyed describing what she felt.
There are other ways to approach this work, but I like to keep it playful and simple. If you like "album write-ups," then
here's one you can check out. Enjoy!