Subtraction of Directed Numbers: Dynamic Number Line Demonstration

① This GeoGebra example dynamically demonstrates the subtraction of directed numbers (positive and negative) on a number line, visually showing that subtracting a number is equivalent to adding its opposite. ② Core mathematical concepts include directed numbers, subtraction, number line, opposites, and sign rules, providing an intuitive geometric model for understanding operations with negative numbers. ③ Construction highlights: using GeoGebra commands Point, If, Sequence, and Corner to build the number line, dynamic points, and interactive buttons; objects such as num0, A, B, dis, button1, n, text1, sign2, text2, sign3, signa, signba, op2, signb, l2, l4, text6, C, f, c, texta, textb, pic1, l5, num1, sign0, sign1, text0, l0, button2, time, button3, correct, answered, t, l6, text11, maxtime, text10, and speed enable interactive feedback, timing, and correctness checking. ④ Suitable for middle school mathematics (Grade 7) teaching of negative number operations, useful for classroom demonstration or student self-exploration, with buttons and sliders to control the process and reinforce sign rules.