The reason why kids can't bring toys to school is because the toys can be a major distraction from them learning things.
Toys when brought to school also create a safety risk and ownership disputes.
And other reasons for toys not being allowed in schools include potential for bullying and conflict as well as the possibility of the toys becoming damaged, stolen or lost, which schools are not willing to be liable for.
Toys can divert the kids attention away from the classroom instruction and schoolwork.
And some toys such as handheld games and trading cards can also be a significant distraction on their own.
Basically toys from home that are brought to school can get lost, cause fights and can carry contaminants.
Years ago I used to bring my stuffed dog toy to school with me and it actually helped me, but now schools don't want kids to bring toys to school.
Toys should be left at home, while the kid is in school and learning.
Some toys also can pose potential choking hazards, cuts from sharp parts or even ingestion of small pieces.
And keychains for example have also been banned in schools because they can be a choking hazard or even a distraction.
Bringing toys to school can also result in arguments, fights and jealousy among kids in school, especially if they have a toy that is identical or the same as the other kids toy.