Before you explain an assignment, let your child read the instructions and tell you what they think the task is. If they are stuck, ask them to underline the part they understand. In a word problem, that might be the starting amount. Give them a moment to decide what to do with it.
If they still need help, work through a smaller example on a separate sheet. For instance, use smaller numbers to demonstrate the same operation, then hand the original problem back. Let your child write the answer in their own words and explain how they checked it.
When the same difficulty comes up again, jot down where it starts. A teacher or tutor can use a marked example to see whether your child needs help reading the instructions, choosing a strategy, or carrying it out.
