Middle School Grade 9 mathematics
Middle School Grade 9 covers square roots and real numbers, trig ratios, circle properties, and statistical dispersion. All 5 activities for this grade are translated into English, with the same quizzes and best-score tracking as the Korean site.
🔢 Number & operations
Square Roots & Real Numbers Lab
See exactly where a square root sits on the number line and practice simplifying radicals.
Open English lesson → 📏Why Is √2 Irrational? Lab
Follow the contradiction that arises when we assume √2 can be written as a fraction, and prove that √2 is irrational using proof by contradiction.
Open English lesson →📈 Functions & graphs
Quadratic Equations and the Quadratic Formula Lab
Use the sign of the discriminant D=b²−4ac to determine the number of roots first, then use the quadratic formula to solve even quadratic equations that cannot be factored.
Open English lesson → 🏀Projectile Motion Lab
Adjust the launch angle and speed, fire the ball, and see how its parabolic trajectory is connected to the quadratic function y=ax²+bx.
Open English lesson →📐 Shape & measurement
Trig Ratios (Sine, Cosine, Tangent) Lab
Choose an angle and which side to fix, and watch how sin, cos, and tan change.
Open English lesson → ⚪Inscribed Angle Lab
Move a point around a circle and see why the inscribed angle always stays exactly half the central angle.
Open English lesson → 🔵Circle Properties Lab
Explore how a circle relates to a line, sector arcs and areas, tangent lines, and inscribed polygons.
Open English lesson →📊 Data