PrepOK

Drag a point around the Cartesian grid to read its (x, y) coordinates and quadrant, snap to whole numbers, and reveal its reflections across the x-axis, y-axis, and origin.

Hover or arrow-key across a 12×12 multiplication chart to light up any times-table fact, with an area model that shows why a × b is a rectangle of that many squares.

Drag a point around the unit circle to see the angle in degrees and radians, plus sine, cosine, and tangent — with exact values at common angles like 30°, 45°, and 60°.

Pick any element from hydrogen to krypton and watch its ground-state electron configuration and Bohr shell diagram build up in Aufbau order — including the chromium and copper exceptions.

Explore all 118 elements in an interactive periodic table: recolor by category, state, or block, and open any element for its electron configuration, Bohr model, and uses.

Slide across the 0–14 pH scale to see each value's acidity classification, its hydrogen-ion concentration [H⁺] = 10⁻ᵖᴴ, and a familiar everyday substance at that pH.

Set any two of voltage, current, and resistance and watch the third solve itself with V = I × R. A live circuit lights a bulb whose brightness tracks the power.

Animate a travelling wave, adjust its amplitude, wavelength, and frequency, switch between transverse and longitudinal motion, and watch wave speed (v = f × λ) and period (T = 1/f) update live.

Slide along the electromagnetic spectrum from radio waves to gamma rays and watch wavelength, frequency, and photon energy update together — with a rainbow swatch in the visible band.

Click or tab through a labeled animal cell to explore the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, ribosomes, lysosome, vacuole, and more — each with its job explained.

Click through an interactive water-cycle scene — evaporation, condensation, precipitation, and collection (plus transpiration and runoff) — with a kid-friendly explanation for each stage.