I agree with not pushing him.  Simply having the right materials around might be enough to encourage him to one day play around with it.  For years, my oldest daughter had me reading shark and whale books ad nauseum (sp?), peppered with some fiction here and there.  She's a really good listener, too, so I kept trying (and failing) to introduce other stories to her.  I didn't push either, simply asked her, though I'm sure that sometimes my frustration with not being able to move past these was visible.  I did love learning and reading about sharks and whales, I just wanted..... more.  Then along came dinosaurs, which I introduced because I knew she loved predators with teeth.  (When I say "Introduced" I mean I borrowed the books from the library and showed them to her along with the other books in the pile.)  Soon we were reading tons about dinosaurs.  Then I got brave and introduced dragons.  I found a copy of The Hobbit with Tolkein's picture of Smaug lying on his treasure and she was hooked.  We read the How to Train Your Dragon series through 5 books, then she was onto monsters.  For that I found loads of Greek mythology books.  I finally introduced her to Harry Potter-- the basilisk and the dementors being strong motivators-- and now she is doing magic all over the house.  She even loves Marcia William's Shakespeare versions--especially the ghost stories.  So, it took a while, but we are finally are reading fiction!  (Jim Arnosky is a fabulous writer and illustrator, whose books for children span the divide between science and fiction.)
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As for art, one way you can tie it in is to approach it in light of science, through field notebooks. Â A pencil box filled with plain and colored pencils, a small, stiff-backed sketch book, a magnifying glass, binoculars and some measuring tools all stuffed into a backpack and taken on a hike are a great way to practice this. Â Sometimes art can be too open ended! Â Even in art class, sometimes it can be easier if you have some limits on the materials you can use, what there is to represent. Then with kids, you give them paper and some paint and the art really *is* just playing with the materials. Â This can be a good thing, within reason (like paint staying in the general vicinity of the paper!) Â I remember as a kid being so frustrated with watercolors, in part because I never really let myself explore the characteristics of the medium. Â I wanted it to be accurate as a pencil right off the bat. Â I'm sure some performance/interpretive artists would beam with pride at their son wallowing in paint!
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So, while of course you want to continue to expose him to those things he seems to be missing, to give him opportunities to discover them and try them out, it is not the end of the world for him to not be on board, especially when there is so much resistance that could potentially derail so many other good things. Â Eventually, he will get exposed. Â Certain phrases are part of our lives, and often those phrases come directly out of literature. Â Science books are filled with photographs and drawings that are art in themselves. Â We just read a great picture book "For the Birds: the Life of Roger Tory Peterson" by Peggy Thomas. Â (Peterson is the father of the modern field guide.) Â What I liked about this story the most was how he followed his own heart. Â He wasn't homeschooled, but this was still an inspiring story for this homeschooling mama--how he saved for a year to buy his first camera, etc. Â He was a great artist and a great naturalist.
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You see, everything is so intricately tied in together that if you can notice it, and ask those questions, they can lead you to exploring those missing elements without even realizing it. Â (How *do* they take those pictures underwater? you could ask.) Â Commenting on a painting of a bird in a science book-- wow, I like that picture!-- is art appreciation. Â I liked the previous suggestion of a camera. Â I have a notebook where I document all the wild plants on our property, complete with my photographs. Â My 7yo is forever borrowing the camera, and some of those pictures are really fabulous (and thank heavens for digital and a 4GB memory card!) Â The ideas are endless, and they don't need to be pushed.