Geometrical Meaning of Derivative: Slope of Tangent

① This example dynamically illustrates the geometric meaning of the derivative of y=f(x) at x=a, which is the slope of the tangent line to the curve at that point. ② The core mathematical concept is the relationship between the derivative and the slope of the tangent, involving function graphs, tangent lines, slope measurement, and the underlying limit idea. ③ Construction details: using GeoGebra commands Point to create points A and B on the function, Line to draw the tangent at A, Slope to measure the slope of the tangent and display it as m, with text1 and text2 for labels, and a slider 'a' to adjust the tangency point. ④ Suitable for high school calculus introduction or college elementary calculus, helping students visualize the definition of the derivative, and useful for classroom demonstrations or self-study exploration.