We never learned this in school

Education is a strange thing when you think about it.  We learn how a lot of things are supposed to work but we are often told in practice that it's not the way things actually work.  We learn about social constructs, geography, ideology, and politics, all of which are concepts that rarely work in practice the way they are meant to work in theory, but we don't focus enough on the actual practical applications of what we learn.

I have a degree in Computer Science with Games Technology as well as a diploma in Computing and Software Development and one thing that has always been apparent to me is that the methodologies and the paradigms that we studied often laid out developmental approaches that were never actually followed in practice.  The most ubiquitous example at the time I studied was called the 'Waterfall Model' and set out a methodology for developing software that was considered de rigueur; yet no-one actually used it and it's still quite irrelevant today.  The Waterfall Model consisted of stages in development that upon completion formed the basis for the next stage, allowing development to "flow" to completion.  There were many problems with using the theory in practice but right now it's not relevant to go into detail.

The programming and design world eventually gave up the pretence and accepted that this wasn't the way things worked in practice.  Other models that were more accurate depictions of the development process gained more acknowledgement.  One example today is that of Scrum Development, where the stages are very loosely defined and the model itself reflects the fact that parts of development are haphazard and involve a lot of rapid revisions and testing.  This shift away from unrealistic theoretical models into acceptance of practical models really changes what a student has to actually learn about development.  The most important being the redundancy of learning models you will never actually use was eliminated.  Now like any academic institution, the course content you study will vary so there will of course be many who still teach the old methods rather than the new.  Therein lies the problem with higher education, there is no overall standard to conform to, and within each field there will be wildly antagonistic approaches taught in different places.

Going back to lower levels of education however the same can be considered true for much of the national curriculae around the world.  Things such as long multiplication have a wide range of methods that can be used to achieve the result.  Which you are taught will vary widely.  "New Math" in particular is a point of major contention as it takes very different approaches to solving problems.  Putting aside the argument of omnipresence of calculators and computers, even if we consider this ability one that is essential, the ways you are taught to solve these problems on paper are rarely the way you work the problem out in your head, returning us to the same disparity between theory and practice.

The problem with all of these variations is that they all tend to focus on what someone else has decided they want you to learn.  Not what you actually need to learn or what you actually want to learn.  That last point is one of the major obstacles to engagement in education - people do not want to engage in education to learn what they are not interested in, and what they won't actually need.  At University when we discussed elective modules one description was used a lot was to refer to how "dry" a module's content was perceived to be.  A dry module was considered to be one that was very boring and hard to engage within.  In college and university the most prominent examples of these were systems analysis and object oriented analysis; both of which relied heavily on theory, most of which you would never actually use in practice, and would never actually need to know.  To that end there was even a discussion whether there was an element of snobbery present within the education system, that such concepts were only taught so that you could say you knew and understood them, providing you with something to set yourself apart from others.

Studying English Literature in school is perhaps an example of this too, whereas English Language deals with the language itself and its constructs such as grammar, lexicon, and articulation, the literature courses deal with the cultural side of the language focusing on historical works considered to be worthy of merit - again a decision made by someone else - and analysing these in a critical manner.  The problem here is that in practice you'll not need to know any of this.  It is arguable that cultural enrichment shouldn't be something left to schools to teach, but rather for the student to explore for themselves.  Shakespeare as an example is something which your interest and excitement over will depend to a great deal on who is teaching you and their approach.  Beyond a very limited number of jobs that actually specialise in Shakespearean literature, the vast majority of the population will never need to know who Romeo and Juliet were - that element of snobbery rears its head again when you find two people, one who does and one who does not.

If person A knows who Romeo and Juliet are and person B knows how to file a tax return, which person do you think is more likely to succeed?  I'll admit their are incomparable examples of knowledge however it would take the same length of time to study both to a basic level.  30 minutes is all it would take to recount the story of Romeo and Juliet and have a basic understanding of the themes.  30 minutes is all it would take to read through a personal tax return form and have a basic understanding of the process. 

So here's the question, how do you decide what is essential education and what is surplus?  As I said most of what you learn is decided by someone else, and in most cases you will never actually meet that person.  What has made you think to yourself "we never learned this in school" and wished you had?