Unless you spend a lot of time with children, you don't really appreciate how much of a big deal it is when a child actually reaches the point where they can pick up some building blocks and stack them on top of each other.
S has been fiddling about with her blocks for weeks; she had four plastic ones that came as part of another toy, and was experimenting with stacking them. Unable to resist, I bought her a pull-along cart with 20 or so coloured wooden blocks. Mostly, she just threw them around the play mats.
Eventually I got sick of finding them and putting them away in the box every evening, or tripping over them (or standing on them!), or finding them in my shoes or in the kitchen or on the sofa. So I put them in the box and just sort of hid them in the corner.
The last couple of days, she's found them - but she's only taken about 6 of them out of the box. I noticed this morning while I was running about trying to get ready for work, that she was happily sitting on the mats, stacking the blocks up neatly. Once she'd succeeded in stacking them, she would gleefully knock them all down, then put her hands to her face and say "oh no!"
This evening after tea, she went straight back to the mats and started stacking the blocks again. I have to say, it was a real lesson in tenacity and patience to watch her stack three, accidentally knock them over whilst reaching for another - and just happily start from scratch. Again, and again, and again.
It sounds stupid but I am so incredibly proud of my little S that she managed to stack six whole blocks on top of each other... before giving herself a little clap and knocking them down with a great big grin!