Как правильно ? at the lesson или on the lesson

On the lesson-на уроке

At the lesson отвечаю

- is the first cake tasty?

- yes, it is.

 

- was the fourth lesson difficult?

- yes, it was. 

A)          if the weather is fine and warm i will go for a walk with my friends. b)          if the weather is cold and windy i will stay at home and play computer games. c)          if the weather is rainy i will visit my friend and watch tv with him. d)        if i don’t like the weather i will read an interesting book or play chess with my father.