Hi Bella! It’s completely fine to fall behind in year 10. Try and stay concentrated in lessons and do all your homework.
I often used to fall behind in your 10 and I fixed this by catching up on the things I didn’t know. Make sure you use you exam boards specification as that will be very useful! Year 11 is a bit of a jump ad you will be put under more stress. Make sure you know and understand all your year 10 content as if is going to come up in your GCSEs. Hope this helps!