When should you use on/in/at?

On is for when we are physically touching something: dates, days, social media, devices, and transport (that we can stand up on). “He is on television.”

In is for when something is inside another thing: “My food is in the microwave.” Or for transport that we have to sit down in (a car).

At is for a specific time or place. We also use it after an adjective: “I’m good at English.