Experimenting with the senses and developping fine motor-skills

A toddler, a box, needles and a needle cushion or ice cubes and a curious toddler... that's the recipe for some time of quietness for yourself, and discovery for your child! Little N. found the whole thing really interesting: that the ice-cubes eventually melted for instance, that she was allowed to put them in her mouth and found them very very cold and unchewable. For the needles, she had been trying to steal mine for some time, so I eventually pick 5 with colours and gave them to her (under careful supervision OF COURSE! and I do take them away once she is done playing!). She discovered that I was not joking when I told her needles sting ;)

 What about you? What do you do with your children?