As this is the peak time when your daughter is facing physical and mental changes that turns her ego level higher. Though, it differs from child to child according to your compatibility and communication. Being a mother if you are close to her like a best friend then you can directly tell her that her writing is poor and need to improve it anyhow.
Whereas, if you are not much closer to her due to having a hectic schedule or any specific reason, it would be better to guide her indirectly in different ways.
• You can tell her that, earlier your writing was very poor, during teenage but you improved it through practising daily.
• You can also tell her that a student gets better marks if their writing is more fair and beautiful.
• You can compete with her that let’s see who writes better and inculcate them how to improvise it every day.