Both my children are in mixed classes at school. The youngest in group 3/4, the eldest in group 4/5. At times the youngest overhears what is being taught to the other group. So she heard that they learned about consonents and vowels (in her class, they just start reading!). So at home she wanted to know what the difference is between consonents and vowels. Try to explain!
Though I could mention them (B = consonent, O= vowel), I found it hard to explain why a consonent is a consonent and why a vowel is a vowel. For my eldest daughter, this was easy. Since she had learned it in school a year ago, it was very easy for her to explain.
This shows that at times it is easier to learn from a person who has recently gone through the same process. The experienced person may have internalized the use and may not be able to explain how he/she makes certain distinctions or decisions.