The question "what is worth learning?" is one future educators should have on their minds. The answer will vary from teacher to teacher and will have to adhere to the rules of whichever educational philosophy the district of your choosing follows. In my opinion, there is nothing not worth learning, especially in today's society. Explicit curriculum is taught in every classroom, it is the intended plans, objectives, and content the school expects you to teach. Its' focus is mainly aimed towards reading and writing skills. The null curriculum is the pieces of history that are relevant but didn't make the cut to get taught directly in the lesson plan. The hidden curriculum is the information that lies under the surface of what is being taught. It's full of ideological meaning and can be inferred based on your own experiences.
Teachers will always teach the explicit curriculum, but they get to choose whether or not they bring the null curriculum or the hidden curriculum to their student's attention. I think it's a good idea to share pieces of information from both the null and hidden curriculum to a certain extent, based on the student's maturity level. Sharing information from both will allow the students to draw their own conclusions on many situations in history instead of just being told what's right and what's wrong. I personally didn't learn about many important parts of history until college and it has changed my perspectives on many subjects in a positive way and I think it should be taught sooner in the educational system.