Why do high school students have a difficulty in physics and mathematics?

I think it's because their mental concept of what “understanding something” means is not adapted to those subjects

One of the reasons for the difficulty of mathematics and physics among students is the failure of the lecturer to communicate information in a simplified and easy to make them love the subject and do not alienate them and improve their mental skills in these subjects ... 

Not my field, but I will answer - I guess, not all of them do. There are those who are great at Math and those who are lousy - it is all only down to the issue of their predisposition 

from my point of view, i think it's because they don't practice very will every lesson they take, and since physics and maths are two interrelated subjects, that means you can't understand the current lesson if you didn't understand the previous one, plus that some countries teach these two subject in a second language different than the native language, which may be difficult for some students who couldn't understand what they really study .

We should not use digital methods/tools to explain the topics.

Teaching technology should be improved and more expirments and demo oriented it should be.

More examples should be discussed and the same problem should not be repeated more number of times.

Mathematics and Physics are very interesting subjects if taken in as above teaching methods.

I teach my kids on more practical methods than on theoritical explaination by just readiing what is given the book.

The human brain is a complex and divergent organ from one individual to the next.  Because each person's brain operates differently and has different pathways of knwoledge acquisition and mastery, some people may have a natural aptitude for maths and sciences, while others may not have that natural ability.  Mathematics and physics can be challenging for some people and without adequate support and materials

I think that many textbooks for mathematics and sciences like physics are not easy to read or understand easily without an effective teacher's guidance.  Often they are written by teachers and professors who have a great understanding of the technical fields, but may have difficulty expressing it in terms that all learners can access.  Some teachers are able to help students bridge the gap between the technical knowledge (the raw numbers and formulae) with something they can understand.  When maths and sciences can be made "real" to students (have real world applications), the students may be able to surpass the limiting view that they can't do the problems.

Maths and sciences may never be easy for some, but should be accessible to all if proper materials and teaching methodologies are employed.

 because most of the students are being planted the mentality of how hard the subjects are with either their friends that have already finished high school level.