Self-studying

in, on, at - place

In is used to talk about position inside larger areas:

Your new shirt is in the wardrobe.

On is used to talk about something’s position on a line or flat surface:

It’s on the top shelf in the wardrobe.

At is used to talk about a ‘point’ rather than a space, and events where people gather:

Write your phone number at the top of the page.

I met him at the Spice Girls concert.

in, on, at - time

At is used to specify a point in time:

I’ll meet you outside the cinema at 7.15.

In is used to talk about a longer period of time (the morning, the summer, 1972 etc):

During the holiday, I usually read in the morning and go to the beach in the afternoon.

On is used to refer to particular days and dates:

It’s Michael’s birthday on Saturday.

In is used to say how much time will pass before something happens, and to talk about how long something takes:

Hurry up, we’ve got Aerobics class in 20 minutes.

I managed to get to Level 3 of Tomb Raider in about half an hour.

With certain expressions with determiners (this, that, some, all, every) and before next and last, there is no preposition.

How are you feeling this morning? You weren't very well last week, were you?

to, into, from, out of - movement

How far is it from the guesthouse to the beach? If you climb into that hole you’ll never get out of it.