Oh fun! Didn't think to do this one, we did one with some flowers we picked up from outside (after they'd fallen off the bushes because I don't like picking flowers) and putting the stem in a jar with food colouring and watching the flower change colour as the water was drawn up the stem. This one looks like fun, might have to try it with youngest if I remember to collect enough containers :)
Right! We did the same with celery sticks before too. These experiments are so fun!