We're doing a cress experiment in Year 1 and after planting it on Friday already the cress that's grown in the dark has grown the most. The cress that has everything (water, warmth, sunlight and nutrients) has grown a little bit, and the other 2 (in the cold and in the sand) haven't grown at all. There's loads of cress in the dark one, more so than the one that has everything. I know about it not being as green because of the lack of sunlight/chlorophyll but how can I explain about the fact that it's grown at all? I can only think that it's growing towards the tiny gap where the light is coming in because it's striving to get to the sun - plus I know I'll be able to physically show the kids this because it's literally bending over towards the gap. I've tried googling but can't really find any child-friendly terminology. Any help would be much appreciated!!