One of the things that people need to realize is that there are developmental levels that are not determined by age. Some ages tend to coincide with certain stages, but it’s not always true that a 6-year-old is ready to learn to read. I taught first grade in public school for 5 years, and I encountered plenty of 6-year-olds there who were not ready to read. Several of my own children have not been ready to read at 6. Some of them were. It has not been a matter of intelligence. It is just readiness and differing paces of development. My latest readers are extremely intelligent. They can remember details of what they’ve read, and they understand how to relate new information with what they already know so that the learning is thorough and in-depth.
To minimize stress and frustration, I wait until my children exhibit signs of readiness before I try to teach them to read. I expose them to letters and sounds from the time they are toddlers, but I don’t expect them to read words until they show me that they want to and that they understand that letters go together to make words. I do this with other subjects and topics, too. Trying to force them to learn something is never optimal. They may learn it for your “test”, but if the knowledge never becomes their own, they are not likely to retain it.