Because current teaching has many forms, all of which emphasize giving students knowledge that can be used as learning skills for educational benefits. Therefore, there are many sources of knowledge arising.
Because the current teaching methods are diverse, all of which emphasize learners' knowledge and skills. Education, so there are many sources of knowledge.
Due to the variety of teaching forms today, each form emphasizes that learners master knowledge and can turn it into learning skills with educational benefits, thus generating rich knowledge resources.