Finally, we have ‘at’. I’ve put ‘at’ at the end as I think it’s the easiest one to learn. At means a time or a place for example, I need to be at school (place) at 9 am (time).
Easy peasy! Take a look at my examples with pictures, they show you when exactly to use at.
So, now you’re a preposition pro, right? I guess now you’ve got to the end you’ve forgotten when to use ‘in ‘ and ‘on. Go back through them again to really ingrain them in your brain.