Read words with ou and ow spelling the same "ow" sound, as in cloud and cow.
Ou and ow can spell the exact same sound -- the one you make when you say "ow" because something surprised you. Ou says this sound in the middle of a word, like cloud. Ow says the very same sound too, often at the end of a word or before n, like cow and brown.
A small heads up: ow can sometimes say a different sound too, long o, like in snow. For now, try the cow sound first on a new ow word, and if it does not sound like a real word, try long o instead.
Mastery looks like: They read ou and ow words with the correct sound automatically and check context when a word could be read either way.
Common stumbles: Reading ow as long o out of habit when it should make the cow sound, or the reverse, without checking that it sounds right.