ProProfs Quiz- their, they're, there or Their, They're, There (use a capital if needed) 

These are homophones = they have the same sound but different meaning and spelling.
Use memory tricks to help remember which one to use:
they're = they are (in the quiz use the short form they're)
there = place or there is /there are. Can you see the word within a word?
here in there = here, where, there.
their = possession- my phone, her phone, his phone, their phone.
Can you see the i in their ? Use that as a memory trick: my (I) phone, their phone.