What are ways to prove that a training program is working or not in a company?

I'm proposing that companies should implement age diversity training to their employees in an effort to bridge the generation gap.





How does a company monitor this effort to see if it is actually working to see if they should continue it or not?





I can only think of surveys for participants to fill out but what else?

What are ways to prove that a training program is working or not in a company?
I think that the company should just modify their training program so that everyone would understand the training. It would be cost effective than several different training programs. At the end of the training session and during the training session ask them if they understand and maybe do small tests and the end of each segment to make sure they understand. They will show you who needs extra training or where you may need to change the training to help them...