Hello everyone, The context is as follows. The teacher explains to the students how they can get a fire using a battery, a chewing gum and cotton wool. When he explains things he actually does them. And when fire appears, the teacher says, "This is it. Now you can see how a/the knowlede of elementary physics can help you in your daily life." What article should be used before "knowledge" in this case? Or no article is required? Thank you.