Mathematics is reasoning.
It was created by reasoning and depends on reasoning for its further development as well as its usefulness.
Reasoning is one of the four proficiencies in the national curriculum, which describes it as a capacity for logical thought and actions. Reasoning develops throughout the curriculum and there are identifiable milestones. You can download a summary of Some Milestones in the Development of Mathematical Reasoning.
Mathematics content knowledge is important, but it should be taught and learned in a way that emphasises the process skills, or proficiencies. Then students will not only gain content knowledge but will also learn to think as young mathematicians. They will be well prepared for future learning as well as very competent in using mathematical processes in everyday life.
Reasoning is not problem solving.
You can download Problem Solving versus Reasoning which is a summary drawn from the Australian Curriculum: Mathematics showing how reasoning is different from problem solving.
