I often notice that I'm sitting completely crooked in front of the laptop at school or at home and after a few hours my back always hurts. Do you have any tips on how to sit straighter?
It is completely normal for the muscles to tire quickly under static load.
You can always change your sitting position. So sometimes on an armchair, sometimes on a chair, on the sofa with a notebook on your lap. Suhl upside down / take the backrest up front, put a pillow on the chair… Be creative.
Can help. Also a ball pillow. These are round pieces that are made of the same material as those big balls that you can sit on. There's air in there, so you're constantly shaking a little when you're sitting on it. This means that you also use your muscles all the time, i.e. Rather dynamically load and not so much static.
Nobody can sit up straight all day or stand up straight forever. It's a myth.
You should get yourself an ergonomic chair.
You should alternate between sitting and standing.
You shouldn't sit in one position for long.
Take breaks.
You should do https://www.gesundheit.de/fitness/fitness-uebungen/buerogymnastik/buerogymnastik.
https://www.arbeitsrechte.de/arbeit-im-sitzen/
"The key to this lies in our pelvis, more precisely: in the tilting of our pelvis:"
https://www.fasziengesundheit.net/2018/01/16/gesundes-sitzen-auf-dem-stuhl/
In addition, I find this article helpful:
https://www.tk.de/techniker/magazin/sport/rueckentraining/ruekentraining-koerperwahrnehmung-2008728
