贝蒂的十五岁生日:比例的双重表示——条形图与双数轴
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该范例通过一个名为“Betty's Quincenañera”的生日场景,演示了如何用条形图(strip diagram)和双数轴(double number line)两种方式表示同一个比例关系。核心数学概念是比例与比值的等价表示,涉及将实际情境(如人数、物品数量)抽象为线段长度和数轴刻度。作图要点包括:使用GeoGebra的Point、Segment、Line、OrthogonalLine、Intersect等命令构造基本几何元素,通过Polygon绘制条形图区域,利用Midpoint、Vector、Translate、Distance等命令实现等分和比例缩放,并借助Circle辅助定位。该范例适合初中阶段学习比例、比和百分比的直观理解,也可用于教师演示如何将同一数学关系转化为不同可视化模型,帮助学生建立数形结合的思维。
GeoGebra 命令及参数
Point(Circle[A, a]) → BSegment(A, B) → fLine(C, f) → gOrthogonalLine(A, g) → hOrthogonalLine(B, g) → iIntersect(g, h) → DIntersect(g, i) → EPolygon(A, D, E, B) → poly1, a_1, d, e, bPoint(Circle[B, b]) → FSegment(B, F) → jPoint(Circle[F, b]) → GSegment(F, G) → kPoint(Circle[G, b]) → HSegment(G, H) → lPoint(Circle[H, b]) → ISegment(H, I) → mPoint(Circle[I, b]) → JSegment(I, J) → nPoint(Circle[J, b]) → KSegment(J, K) → pOrthogonalLine(F, g) → qOrthogonalLine(G, g) → rOrthogonalLine(H, g) → sOrthogonalLine(I, g) → tOrthogonalLine(J, g) → cOrthogonalLine(K, g) → f_1Intersect(g, q) → LIntersect(g, r) → MIntersect(g, s) → NIntersect(g, t) → OIntersect(g, c) → PIntersect(g, f_1) → QPolygon(B, F, L, E) → poly2, b_1, f_2, l_1, e_1Polygon(F, G, M, L) → poly3, f_3, g_1, m_1, l_2Polygon(G, H, N, M) → poly4, g_2, h_1, n_1, m_2Polygon(H, I, O, N) → poly5, h_2, i_1, o, n_2Polygon(I, J, P, O) → poly6, i_2, j_1, p_1, o_1Polygon(J, K, Q, P) → poly7, j_2, k_1, q_1, p_2Intersect(g, h) → RLine(A, R) → r_1Point(r_1) → SOrthogonalLine(S, r_1) → s_1Intersect(r, s_1) → TSegment(S, T) → t_1Intersect(f_1, s_1) → USegment(T, U) → c_1Midpoint(S, T) → VMidpoint(T, U) → WPoint(r_1) → ZPoint(r_1) → A_1Segment(Z, A_1) → d_1Point(d_1) → B_1Point(d_1) → C_1OrthogonalLine(B_1, d_1) → k_2OrthogonalLine(C_1, d_1) → q_2Point(k_2) → D_1Vector(B_1, D_1) → uPoint(q_2) → E_1Vector(C_1, E_1) → vPoint(u) → F_1OrthogonalLine(F_1, u) → r_2Point(v) → G_1Point(d_1) → H_1Vector(H_1, F_1) → wTranslate(F_1, w) → I_1Translate(I_1, w) → J_1Translate(J_1, w) → K_1Translate(K_1, w) → L_1Translate(L_1, w) → M_1Translate(G_1, w) → N_1Translate(N_1, w) → O_1Translate(O_1, w) → P_1Translate(P_1, w) → Q_1Translate(Q_1, w) → R_1Midpoint(d_1) → U_1OrthogonalLine(U_1, d_1) → t_2Point(Circle[U_1, ((a * 3) * 40.36 / 18)]) → V_1Segment(U_1, V_1) → a_2Point(d_1) → S_1Distance(S_1, R_1) → distanceS1R1Point(Circle[U_1, ((distanceS1R1 / 18 * 3) * a)]) → T_1Segment(U_1, T_1) → s_2OrthogonalLine(T_1, t_2) → b_2Circle(T_1, 4) → c_2Intersect(c_2, b_2, 2) → W_1Intersect(c_2, b_2, 1) → Z_1Segment(W_1, Z_1) → d_2
AI 绘图提示语参考
绘制一个由水平基线和上方平行线段构成的矩形条带图,表示比例关系。首先画一个矩形,将其底边等分为七段,每段长度相同,并在各分点处向上作垂线,将矩形分割成七个等宽的小矩形。接着,在矩形上方画一条与底边平行的直线,从矩形左端点出发,用相同单位长度依次向右标记七个等距点,并过这些点作垂线,形成一条双数轴。最后,在矩形左侧添加一条辅助斜线,并在其上取一点,过该点作垂线与矩形底边相交,连接相关交点形成一个小三角形,用于展示比例的另一表示。
以上提示语为根据原始绘图命令整理而来,仅供参考。