How old are the children of Mo You Calligraphy Online School suitable for learning calligraphy?

Look at their APP. It says that it is aimed at children aged 5~ 15. My son learned it in Mo You Calligraphy Online School in the third grade this year. Their national standard regular script teaching is very good and professional. This font is also suitable for children to get started, and it is very standard to write. When children learn to write, they should start with the most standardized fonts and lay a good foundation.