When we talk about today’s education system, it is really too much annoying. 
In the old days, when Gurukul’s ran the schools, I won’t say that it was perfect. Gurus only used to teach the students with higher status of Brahmins or Kshatriyas. Lot many students remained uneducated. For Eg. In Mahabharata, Eklavya and Karna were denied of education because they did not belong to the higher communities.
Nowadays, all students are getting Education, but all students study the same subjects. There is no choice of interest. If a student starts learning his / her subject of interest from the age of 8-10 years, he / she can become more capable, as the learning age is actually within 5-14 years only. After that they don’t learn but they experience the things. My suggestion is that the choice of subjects should be decided at the age of 8-10 years itself so that the interest is developed on time and the final product when comes out is full of knowledge and experience which can be a reward for the world. Or if we are not able to change the system overnight then we can identify the skills of the students at an early age and make them concentrate on that.
If as an adult, teacher can’t teach all subjects, then as a child, how can we expect students to learn all subjects?