Don't worry if you have moved schools you will be able to move your Sumdog account to your new school too. This way you will not lose any coins or have to start over.
Your parents might need to speak to your old teacher to ask that they remove your student account from the school.
Once that has been done you will be able to request to join your new school.
This is what you will need to do from your student account:
If you see this message it means that you are not part of a school or family.
If you know the school code for your new school you can click on 'join another school'. You will then need to key in your school code to request to join that school.
The teacher will then need to approve your request and add you to the class.
If you do not know the school code yet, don't worry you can click on 'Remind me later' to continue to play Sumdog.
Once your new teacher has given you the school code you can:
1) Log into your student account
2) Click on the House panel
3) Click on your profile panel (the top panel on the right with your name)
4) On the bottom left of the page click on Settings
5) You will now be asked to key in your school code
6) Once ready click on Request to join school. This will send a request to your teacher who will then be able to add you to her class.