We went for a walk in the rain.
The reader reads ran instead of rain.
Teach a reader to stop if something doesn't make sense. You could ask if it makes sense to go for a walk in the ran. Is a ran something you could walk in? Let's look closer at the word you read as ran.
Teach a reader to stop if something doesn't sound right. Would someone say they went for a walk in the ran? No, this isn't how a person talks. It didn't sound right. Always stop if what you read doesn't sound right. Then you can look more closely at the words and try to fix it.