Teacher is it testicle or stethoscope?

 
True Story:

A pre-school teacher was giving a lesson about Veterinary doctors and what that they did for animals. She raised her book and pointed at a picture of a doctor. 

"What is this that is around the doctor's neck?", the teacher asked her class. 

"A testicle", said a little girl in the back. 

"No, no, children. It is a stethoscope." stressed the teacher while trying very hard to keep her composure.

 As the other children began to think about the thing around the doctor's neck, they agreed with the little girl. Of course, it sounded correct to them. Besides, stethoscope sounds like testicle to the untrained ear of a child. (maybe even a grown up too) 

"It is a testicle", they cried in unison.

"Now listen to me say it, steth-o- scope" she said.  The teacher deliberately sounding out the word for the children, hoping that they will eventually get it.  

It took a while, but the children finally believed that it was a stethoscope. Most importantly, they had the correct word for the instrument.
 

How would you do in this slightly embarrassing situation?