Grammar - time, at / in / on

In = long times (months, years

, or longer)
In July, we can see fireworks.
In 2012, I bought a house.
Dinosaurs lived in the Jurassic period.

On = single days (days of week, holiday, etc)
Christmas is on December 25th.
What are you going to do on your birthday?
Do you have plans on Saturday?

At= specific time
I'll see you at 3:00.
Let's meet at noon.
I'm going to the movies at 5.

practice:

1. Let's get dinner _________ Friday.
2. I like to take a walk every morning ________ dawn.
3. ________ ancient Roman times, soldiers were not allowed to get married.
4. Disco was most popular _______ the 70's.
5. Let's go to the diner _______ midnight.