They are usually are pretty anxious about finals, so I've decided to plan a workshop during their free period. They are usually pretty anxious about finals, so I've decided to plan a workshop during their free period.

They're usually are pretty anxious about finals, so I've decided to plan a workshop during their free period. They're usually pretty anxious about finals, so I've decided to plan a workshop during their free period.

They're usually are pretty anxious about finals, so I've decided to plan a workshop during their free period. They're usually pretty anxious about finals, so I've decided to plan a workshop during their free period.

The workshop will be art- therapy,. I think it would be different than what they already know, and thus, would be interesting for them ! The workshop will be art therapy. I think it would be different than what they already know, and thus, would be interesting for them!

I’m pretty sure you don’t need a hyphen for art therapy.

The workshop will be art-therapy,. I think it would'll be different than what they already know, and thus, would be interesting for them ! The workshop will be art-therapy. I think it'll be different than what they already know, and would be interesting for them !

The workshop will be art- therapy,. I think it wouldill be different than what they already know, and thus, would be interesting for them ! The workshop will be art therapy. I think it will be different than what they already know, and thus, would be interesting for them!

I don't think "art therapy" should be capitalized here. Also, you shouldn't put a space before punctuation marks.

I never tried art- therapy before but I've heard lots of great things about it ! I never tried art therapy before but I've heard lots of great things about it!

I've never tried art-therapy before, but I've heard lots of great things about it ! I've never tried art-therapy before, but I've heard lots of great things about it !

I've never tried art- therapy before, but I've heard lots of great things about it ! I've never tried art therapy before, but I've heard lots of great things about it!

The past perfect sounds more natural here ("I have" = "I've").

Have you tried it before ? Have you tried it before?

Have you tried it before ? Have you tried it before?

What other activities I could I do to prepare to help my students ? What other activities could I do to prepare my students?

“To prepare to help” sounds a little unnatural because they both basically mean the same thing in this context. I would either say “to prepare my students” or “to help my students.”

What other activities I could doI prepare to help my students ? What other activities could I prepare to help my students ?

What other activities I could doI prepare to help my students ? What other activities could I prepare to help my students ?

To form a question in English, you typically invert the subject and the verb.