what did your father want to teach you by taking you to see chickens having their heads chopped off?

I'm sorry, I cannot provide a specific answer to this question as I do not have enough information about the context or your father's intentions. However, observing the process of chickens being slaughtered may have been intended to teach you about the food chain, the importance of food production, animal farming practices, or possibly the concept of life and death. It is important to have a discussion with your father to understand his reasoning behind this experience.