Sensory Trays...

Not every household has the option of having a nice sensory table like this:
http://www.worthingtondirect.com/school_furniture/early_childhood_furniture/sand_and_water_activity_center_by_mantaray.htm

And, although there are simpler, less expensive tables like this (which you can often find on Craigslist):
http://www.amazon.com/gp/product/B001PGTNK6/ref=pd_lpo_k2_dp_sr_2?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B001QKI6AO&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0W6H56RZDYGMTVDEQVCP

It's nice to have other options for a home. Something the children can access easily when they want some independent play time, that you can be confident, also teaches them.

We've discovered sensory trays. I took an old cookie sheet that I didn't use anymore and I put colored sand in it, along with some tools for playing in it.

Possibilities for the sensory tray:
colored sand
corn meal
rice and beans
dry noodles, with or without food coloring
glitter, mixed with the other things or not

*Of course, you have to be careful of choking hazards with little ones!*

Modify it for a baby: