A school samba band is typically a group of 10 to 30 students playing Brazilian influenced percussion on Brazilian samba school instruments. Samba is the carnival rhythm of the samba schools of Rio de Janeiro, but school samba groups play many other (easier) styles of Brazilian percussion on their samba drums. Reggae, funk, and hip hop are popular. The only limit is your imagination.
The samba band is a marching band, but is unlike European and American marching bands in some key respects.
Perhaps the single most important difference is that samba music is an aural tradition. In Rio de Janeiro no community samba band uses musical notation; everything is learnt by ear through persistent practice. If you apply this principal to music performance through a school samba band, you can reach those pupils who have previously proven to be resistant to formal musical education. The samba band reaches parts that other music education cannot reach.
Samba music is part of a carnival tradition which involves costumes, song and dance as well as percussion. In a school context, this gives an opportunity for many different school departments to work together on a single cross cultural project. Costume making, singing, dance and percussion attract different pupils and there will be something in this broad curriculum mix for just about everyone.
To set up the samba band you will need samba drums, but equipping a school samba group is cheap compared with setting up other types of musical ensembles. You will need surdos, caixas, repiniques, tamborins, chocalhos or ganzas, and you can add other instruments like agogos and timbas.
A samba band is noisy and you will need somewhere to rehearse where you will not be disturbing the rest of the school. A common solution is to rehearse after school hours. Another consideration is space to store the samba drums, which needs to be dry and secure.