Dr. Greene's Answer
It can take a while for kids to learn to chew (chewing and swallowing is quite complex), but swallowing food whole can be a choking risk. Cheerios can be nice for practice; a single Cheerio is crunchy and fun to chew. Soon it turns into mush and if they just inhale it, there is a hole in the middle to let air through.
You can also try thin slices of banana or small cubes of carrot, cooked until soft. Avoid whole things that he might choke on. He’s unlikely to choke on a soft-cooked pea, for example, but popcorn, nuts, beans, tortilla chips, raw or undercooked vegetables, grapes, hard candy, hot dogs, and other meats are all common causes of choking incidents.