I think Kindness Boomerang gives us the chance of revising/learning conditional sentences of all kinds.
I would suggest the following steps in the lesson:
- Students watch the video and make a note of the chain of actions in it: the builder helps the skateboarder to get up > the skateboarder helps the old woman cross the street > the old woman gives the girl change for the parking meter > The girl picks up the envelope the man in the suit has inadvertently dropped > The man in the suit helps a man unload the luggage from the car boot > The car man buys a hot dog for the beggar > The vendor gives the beggar water > The beggar gives the girl the mobile she had forgotten > The mobile phone girl buys some flowers for the woman sitting at the cafe > The woman at the flower stall gives a flower to the mobile phone girl > The woman sitting at the cafe leaves a generous tip > The waitress gives a drink of water to the builder.
- First conditional: If the builder helps the skateboarder to get up, the skateboarder will help the old woman cross the street > If the skateboarder helps the old woman, she will give the girl change for the parking meter > ...
- Second conditional: If the parking meter girl picked up the envelope, the man in a suit would help the man unload the car > If the man in a suit helped the man unload, the car man would buy a hotdog for the beggar > ...
- Third conditional: If the beggar had given the mobile to the girl, she would have bought flowers for the woman > If the mobile phone girl had bought flowers for the woman at the cafe, the woman would have left a generous tip > ...