Take, for instance, the identical equation (a + b) @ = a @ + 2ab + b @ which is studied in junior high. If students use graph paper to plot out examples, then it's easy to understand and won't become just a dry, mean ingless formula.
如同國中所學的（a＋b）2＝a2＋2ab＋b2 的恆等式，如果學生夠以圖例的面積弄通關節，就能很自然地瞭解等式，而不是形式化的硬背公式。