Which laptop is suitable for school?
Depends on what you want. If you want to have a normal laptop then one is enough for 400-600 euro, but if you still want to write it, then I would recommend you a convertible or a surface. It's actually worth it, but a laptop is more likely to study because you can't download most of the worksheets at school anyway.
If you want to save, look for a used one with a slightly older processor. It is still better than a notebook and does not cost much more than 350 euro.
see: https://www.luxnote-hannover.de/notebooks/mobil/lenovo-thinkpad-x250.html