It's one of the phrases parents repeat the most: “My child understands English, but when they have to speak, they freeze up”. They recognise words, follow instructions, even get good grades, but as soon as they have to express themselves, they go quiet or answer in monosyllables.
This behaviour is not unusual and does not indicate a lack of ability. In fact, it is much more common than it seems and has a clear explanation. Understanding a language and daring to use it are different processes, and one does not automatically guarantee the other.
