What defines cultural appropriation?

Je
A good few years ago I learnt what it is ( take something from another culture for fashion or fun for example)  so I know it's wrong to go wear braids that on a black woman is 'ghetto' or wear a kimono for fashion. 
But we're having a celebration of Indian culture in school in a few weeks and I'm not sure if that's cultural appropriation. Basically we're experiencing traditional Indian things, for example We're doing henna tattoos, Bollyhood dancing, Listening to Indian Music, having Indian food for lunch etc... 
I'm not sure if it is cultural appropriation because we're not passing it off as something fashionable but I don't want to be involved if it's wrong. So I thought I'd come to you ladies to help clarify if it's okay to do these things or not.

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