People who learn to solve problems 'on the job' often have to do it
differently from people who learn in theory. Practical knowledge and
theoretical knowledge is different in some ways but similar in other
ways - or else one would end up with wrong solutions to the problems.
Mathematics is also like this. People who learn to calculate, for
example, because they are involved in commerce frequently have a more
practical way of doing mathematics than the way we are taught at school.
This book is about the differences between what we call practical
knowledge of mathematics - that is street mathematics - and mathematics
learned in school, which is not learned in practice. The authors look at
the differences between these two ways of solving mathematical problems
and discuss their advantages and disadvantages. They also discuss ways
of trying to put theory and practice together in mathematics teaching.