I've been trying to teach Calder to use the sharpener but with disastrous effects - he would either break the thin pencil lead or dislodge the sharpener from its container. Today it occurred to me to let him sharpen thick colour pencils instead. Wow, there's so much skills involved, including holding sharpener and pencil the right way, pushing the pencil in while sharpening, turning the pencil and not the sharpener etc. Even emptying of the sharpener container is a skill (e.g. not to drop sharpener into dustbin). Calder gleefully laboured over 21 thick colour pencils before he tried sharpening a thin one - lo and behold! That thin pencil lead stayed intact. Successful learning!