Hi!
For science experiments, most people in my school did Bio/plant related experiments (e.g: plant growth, seed sprouting, stuff on light or water, etc...)
They're pretty easy to write reports on and most people who went down that route achieved ~40/45 for their reports.
If you want to, you can do a pendulum experiment. You can find many examples of these experiments online, which is a plus.
I did something on the viscosity of oil: I heated/cooled down oil and dropped a marble down a tube. That was two years ago, so I can't really remember much of it.
Don't stress too much though if none of these strike your fancy: there are plenty more experiments online.
Hope this helps!