I'll assume that this debate question refers to dressing conservatively, not as Catholic martyrs. In such a case, yes, I believe that schools should have and enforce a dress code. Students may be distracting if they dress in certain ways. Growing up, my school had this rule in place for both boys and girls. For example, t-shirts could not promote drinking and drugs, and shorts and skirts had to be a certain length. It helps kids learn respect for school time, and be more serious about their studies.
All students should be forced to dress like saints. In fact, schools should rotate which saint the student must dress as week to week. For St. Francis of Assisi week, the children should dress in a brown robe with animals all around. For St. Thomas Aquinas, brown robes with pillows in them to make them look fat.
Although a dress code is reasonable, students should not be forced to dress like saints. Some leeway is necessary in order to allow kids to express some individuality. On the other hand, inappropriate clothes should be banned. Clothes that have advertisements for drugs, alcohol, or tobacco should not be worn by minors.
Students should not be forced to dress like saints. I think students should be allowed to dress however they want to as long as it is appropriate for class. Everybody has their own unique style and should be allowed to express it. If we start requiring them to wear certain things then we are not letting them express themselves.
I believe it is nonsense to assume that students should dress like saints. There are many saints and they are from varying backgrounds and times in history. Saints dressed a variety of ways depending on what era and country they were from. Should students dress appropriately, 100% yes. So, if you mean should students be disallowed from wearing overly revealing clothing? Then yes, you should. It's not appropriate to walk around with next to nothing on.
Before considering whether students should be forced to dress like saints, we first need to consider what a saint dresses like. I have seen some pictures of saints and some of them look pretty ragged. I am sure it was the clothing they saw fit to wear under the circumstances but in general I doubt they would have worn those clothes to school.
Students should have the right to dress how they want and express how they want to be viewed with their attire. They should not be required to dress like saints, or any other predetermined dress code. All students should be able to express their individuality based on how they dress if it doesn't harm others.