Concept definitions on their own do not show the need and scope for new ideas. Students need to distinguish what is, and what is not, related to any new idea. They need to see non-examples and special cases.
Exercising control over carefully designed software helps students ask powerful questions and develop skills for employment and future study. Using the full range of mathematical tools to aid problem-solving becomes a highly important skill in employment and future study.
Graphical representation is a tool for learning in almost all areas of mathematics as it connects algebraic, tabular, and computational perspectives. 21st century students need to develop the habit of graphing and analysing mathematical and statistical behaviour.