Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Hit and miss

I am taking a CNA class and this was included in the course. A friend was able to use hers just fine, but mine did not work. I could hear the tapping, but no clear heartbeats or lung sounds. I thought it was me, but as soon as I used the ones in the lab, I realized the problem was not me, it was the stethoscope. When an instructor tried mine, she had problems with it, too. Also, the earpieces hurt quite a bit after only a minute. Not great to practice with, even if it "works."