I understand that it is difficult to get a child into LosCris school because it is oversubscribes and popular because of the location.
You do need to sort it quickly because the new school year is about to start. You need to take along the following paperwork :
1) You need to provide one of the following for each parent ;
'Certificado de Residencia' or the Certificate from the Ayuntamiento that you are resident at your address.
Empadronimiento (get this at your Ayuntamiento too).
'Tarajeta Censal' or Census Card (if you are on the voting register you will have this. Also from the Ayuntamiento where you live, if you need to get one).
2) A photocopy of the DNI/NIE of both parents and the child (if he or she has one). This can be the piece of paper you got from the Police station, or a copy of your residencia. It's also a good idea to take the original along with you too... that goes for all the documents listed.
3) Your Libro de Familia and a photocopy of the child's page from it.
4) Photocopy of the 'Declaracion de la Renta' of both parents. This is obtained from the Hacienda near the Green Hospital in Las Americas. Get there early and pull a ticket, as it's one of those queuing jobs! It's basically a tax return, but it's the official stamped one. Tell the people there that you need it for matriculation for your child and they'll sort you out. If you are on the dole you need one, however if one of the parents doesn't work and hasn't claimed, you only need it for the working parent. You will need at least one though, so if you're planning to get your kid into school in the future, make sure at least one of you has a contract of some sort!