This review is from: How to Solve It: A New Aspect of Mathematical Method (Paperback)The issue is that solving problems is not made interesting and fulfilling experience.
This book beautifully explains the process of problem-solving. It starts from simple problems, lays down the fundamentals and leads to more complex problems.
One of the gems is the simple formula:
It is also a good reference to teach kids how to approach problems.
Buy it and it will be a very handy reference.