Narrated Ubayy ibn Ka'b: The Prophet ﷺ read the Qur'anic verse: "Thou hast received (full) excuse from me (min ladunni)" and put tashdid (doubling of consonants) on nun (n).
The lesson here for children is that they should always pay attention to detail when doing something important like reading or reciting from the Quran, as this can make all of difference in understanding its true meaning and purpose. They should also remember that their words and actions are important, no matter how small they may seem at first glance.