I think it is necessary for secondary school students to wear casual clothes when they are at school.

Firstly, casual clothes make all students feel comfortable. They can wear convenient clothes for outdoors and indoors activities. Secondly, casual clothes can give students freedom of choice. They can choose what sizes, colors, and fashions of clothing they love. Moreover, casual clothes can make students feel self-confident when they are in their favorite clothes because they choose these clothes carefully and ensure them to be well-dressed. Finally, it makes the school more colorful and lively with different styles, colors and types of clothes.

In conclusion, in my opinion, all the secondary school students should wear casual clothes.