"Die Lehrer essen Sandwiche."
Take note of the 'Die' and the 'essen'. At singular it would be: Der Lehrer isst Sandwiche.
Here are correct forms for teacher: indoctrinator Lehrer m instructor Lehrer m schoolmaster Lehrer m teacher Lehrer m; Lehrerin f
the word 'Sandwiche' at the end was inaudible/too robotic. I had to skip because I just couldn't hear what it was.