Here is the part that surprises everybody. The surah says: "woe to those who pray"
Ask your child: Wait — isn't praying a good thing?
Read the next line and it becomes clear: these are people who are heedless about their prayer, and who pray to be seen. They stand up nice and straight when people are watching, and forget all about it when they are alone.
So the lesson is not "do not pray". It is: pray for Allah, not for an audience — and let your prayer make you a kinder person.