Classroom Grading Curve Simulator

Raw Class Scores

Class size 30

Raw mean μ 68

Raw spread σ 14

Curving Method

Target class mean 80

Class Outcome

Raw mean

0.0

Curved mean

0.0

Passing (≥60)

Points added

0.0

How it works

Each student's raw score is drawn from a normal distribution with mean μ and spread σ, clamped to 0–100. Curving transforms every raw score r before letter grades (A≥90, B≥80, C≥70, D≥60, F<60) are assigned:

Linear shift:   curved = r + (target − raw_mean)
Square-root:    curved = 100 · sqrt(r / 100)
Std-dev stretch: curved = target + (r − raw_mean) · (target_σ / raw_σ)

Linear shift — every student gets the same flat bonus so the class average lands on the target; a curve used when a whole test ran hard.
Square-root curve — a nonlinear boost that helps low scorers proportionally more than high scorers (a 64 → 80, a 100 stays 100).
Std-dev stretch — rescales the whole distribution's spread and center at once (a common "curve to a target GPA" technique), which can push borderline students across grade lines without changing rank order.

All three methods change how many students pass without changing who scored higher than whom — the bar chart's left-to-right rank order never changes, only each bar's height and resulting grade color.

A / B (pass with margin) C / D (passing) F (failing)

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