The Order of Teaching the Parts of the Calculus
John K. Lamond, Charles C. Grove, Ross W. Marriott · Mathematics Teacher Learning and Teaching PK-12 · 1917
When the average student reaches the calculus his ideas of a function, a variable, a variable approaching a limit, etc., are so vague, and oftentimes so entirely wrong, that it would seem wise, since the foundations of the calculus rest so largely on the theory of limits, to spend enough time at the beginning of the course to develop the theory of limits in a careful and thorough manner.