When small children develop new skills they like to practise them - a lot!
Yesterday, after C showed some interest in a lever-arch file, Hubby showed him how it worked and then let him have one for his desk. He delightedly ran off to his bedroom with it and spent most of the next hour carefully opening and closing it, and inserting and removing paper - one piece at a time.
With Bug, she has two current development skills to work on. The first is her speech. She points to anything that she knows the name of, and shouts out the name. At mealtimes we are informed that this is her "plate", "spoon", "fork" and "dink" (drink). The other skill which she is practising is dressing and undressing. Go in to her bedroom in the morning and her pyjamas are in various orientations - pyjama trousers off, and the top, well she might have got her head out but arms still in, or arms out and head still in, or she might have managed to get it all the way off. She loves pants (I'm in the UK so these are underwear). If she's in C's bedroom she'll quite often go into his wardrobe and fetch a pair of his pants to put on. We tried her in her own pants last week, but I don't think we're quite ready yet. Today as I was ironing, she was taking items out of the ironing pile and putting them on... so she had a vest and t-shirt, then a pyjama top, and then a dress over the top. Then she went and fetched a hat and some shoes as well!