I think we owe it mostly to the Leapfrog Letter/Talking Word/Storybook Factory videos. Those are a terrific resource for children just figuring out the letter-sound code and how to apply their new knowledge. We own some Leapfrog letter fridge magnets, so dd5 and dd2 have been playing with them after watching the videos.
The concept of digraphs has started to really sink in for dd5. Previously she would see "sh" and say "ssss""hhh" nearly every time no matter how often I reminded her that "sh" says "sh." I suspect a few minutes of looking at this old toy, which we just had sitting around in a toybox, helped her realize that it's OK not to break the letters apart when looking at certain letter combinations:
|Kiddicraft alphabet toy with 4 of most common English digraphs|
|Traditional hornbook example, sold by Plimouth Plantation|
Sadly, the Kiddicraft Flip-up Learning Center is only available used, but if you want one, it appears on eBay sometimes for a reasonable price. I think I found ours at a local thrift store a few years ago.
(I make no money from product placement in my blog posts. I'm just sharing things that I've found helpful.)