Some weeks ago A Clil to Climb published a short but effective explanation of the differences between the prepositions IN, AT and ON for both place and time.
Click on the image below to read Chiew Pang’s explanation before trying an interactive cloze test based on the earthquake that hit Japan recently and where you only have to insert either IN, AT or ON.
To study these prepositions in more detail Chiew Pang recommends this article from OnestopEnglish.