Create this sound by opening your jaw a lot and putting your lips wide apart (similar to a clown face). Your throat will be a little tight. This is not the most attractive sound of standard American, but it is important. As a short vowel, it will have simple spellings–no silent letters nearby.
Use the video to listen and repeat common words.
act, after, as, ask, at, back, bad, bad, black, class, fact, fast, had, half, happen, has, have, language, last, laugh, math, map, pass, pattern, perhaps, that, travel.