Sara, to trip is the act of catching your foot on an object which causes you to stumble; perhaps a carpet or a cat. to slip is an act of losing friction with a surface; think banana skin or ice. to fall is the act of moving towards the centre of a mass as when under the influence of gravity; think, off something. Providing context 'flavours' each of these situations.

Hi Sara, The meanings of 'fall over' and 'trip over' are about the same. The difference is grammatical. We can say 'I fell over' as a standalone phrasal verb. But 'trip over' isn't a phrasal verb... so if I say 'I tripped over', because I've included the preposition 'over', I need to include its object (the object of the preposition). So, someone falls: I don't know what happened; he fell over! I don't know what happened; he fell over the edge of the cliff! He tripped. He tripped over that rock. NOT: He tripped over the edge of the cliff (here you can see 'over' acting as a preposition and not as the particle in a phrasal verb... and you can't really trip over the edge of a cliff, which is why this sentence doesn't work). AND NOT: He tripped over. 'Slip' is different and is usually used with 'on', as in 'He slipped on the ice'. I hope this helps!