Apostle Paul Wrote Acts?

Sometimes, it can be rather humourous (and upset as well!) to read what the students write in their papers. One of my students and I just had a good laugh when I pointed out what he wrote in his paper:

"When Paul writes to his Gentiles converts in 1 Thess 1:9 and Acts 14:15, he reminds them...."

I asked, "Paul wrote Acts?"

He answered, "Oh my, why did I write that...I deserve a big slap from you...."

I should have done just that! Why did I let him go?