I love to encourage the children to just paint whatever they like with watercolours/poster paints. As mentioned elsewhere on this site I have a particular dislike for ready-mixed acrylic paint! Apart from the mess and tidying up, it has such a bold, flat, unnatural appearance. Granted, it has its place, and if you need to cover a large area fast with thick colour, it’s the way to go.
I occasionally set up a still life, and even join in now and then. I think fine art encourages some different skills to craft activities, albeit with a decent overlap. A higher level of hand-eye co-ordination is probably demanded by fine art, and a greater freedom of expression is allowed.
This is not much of a still life, since there’s not time in our house for setting up elaborate displays. I intended to add some lovely large autumnal leaves that were sitting all of three feet away… but alas I forgot. So the home-grown peppers and tomatoes were supplemented with some other fruit and veg and then we all had a go. There are only two guidelines in my book: the first is to paint what you see, not what you think it should look like. And the second is to avoid using black. We had a lot of fun.