Grammar check please....

[Yankydoodledandy]

so is it....

1. part of
2. a part of
3. apart of

makes them feel part of a team instead of the "odd one out".

'Part of'.

I want you to feel part of the team

I want you to feel a part of the team

Yes definitely 1

1. 2 would be okay too. Definitely not 3.

Apart means the opposite so that's definitely wrong.

Part of is slightly more informal than a part of, but both are correct.

UPDATE...

Ok sorry should of put the whole sentence - another question

..makes them feel part of a team instead of the "odd one out"
OR
makes them feel part of a team instead of being the odd one out"

Either is fine. If in doubt I usually go for the more concise option.

I'd say the 2nd one unless someone has specifically said "odd one out" in some sort of pointed way.

Either is fine, but it's "should have" not "should of" (just so you know).