How to randomly assign an odd sample!?

Question

My sample is English honors student and i have 11 classes as samples. There are two treatments so i have to divded the classes into half randomly. The problem is, there is an odd number of samples! Iono what to do. Could you guys help me? Thanks!
I thought of eliminating the 11th class and randomly assign only 10 classes. Also, i thought of randomly select one class to divide into two. Do you think this is random? How about having the teachers of each class randomly select a treatment (probably by selecting a piece of paper).

Answer 1

Create a 12-th (do nothing) class.