Although Sensory Tubs are not exactly Montessori style, my kids absolutely LOVE them-
Just pick a theme and fill the box up with any little tidbits that pertain to that theme. The idea is to let the kids touch and feel and use their imagination to create whatever it is they want to do with it.
At first, I didn't quite understand the concept. Put a box of rice with some toys, a magnifying glass and then what? But after making our first Sensory box, I gave it to my 3 year old daughter and just observed her. She sat there for about 30 minutes, maybe more, just sifting through the sand (it was a beach theme) then she picked out all the shells and lined them up. She took the fish, people and birds and had a whole situation going on. She absolutely loved it. So now, each time I make a new box, she is SO excited to explore whats inside. I think it would be good to switch themes at least every month, keeping things exciting.
Check out our 6 Days of Creation Sensory Tub:
sand for the land
blue glass stones for the water
plastic fish and duck in the 'water'
miniature animals on the 'land'
Wooden sun and moon
Boy and Girl for Adam and Chava
Here is a link to the post that contains our Rosh Hashanah Sensory Tub:
Given our rich Jewish heritage, there are endless ideas of Jewish themed Sensory Tubs- just think of each Jewish Holiday, different Mitzvot (Kosher, Shabbat, 10 Commandments etc.) and find objects around the house that connect to the theme. And its always nice to fill them with different things like glass beads/marbles, rice, lentils, feathers, pebbles, sand- there are lots of blogs out there with some great Sensory tub ideas. Just google "Sensory Tubs".
Set it up in a way that each object is clearly displayed for the kids to see, then let them play with it however they wish. Its okay if they mess it all up and mix it together. They are learning and exploring and having a great time. But I should advise that setting up some ground rules is a must: they can take the bigger objects out of the tub but need to return them when done. They CANNOT pour the sand/rice/lentils/beads etc (whatever you use to fill it with) out of the tub. It might take a few times getting used to, but once they know the drill, its fabulous.
Wishing you all a Shabbat Shalom!