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Classroom

Drawing Question Type

Students draw curves, points, and lines on a coordinate grid for auto-grading.

Basic Syntax

[drawing:function]
answer = x^2 - 2;

Types

function — Curve from an equation

Student draws the curve for a given function.

[drawing:function]
answer = 2*sin(x);

line — Straight line with slope and intercept

Student draws a line by clicking two points.

[drawing:line]
answer = 2*x + 3;  // Slope = 2, y-intercept = 3

point — Single point on the plane

Student places a point at specific coordinates.

[drawing:point]
answer = (3, 5);

piecewise — Multiple curves or segments

Student draws a piecewise function.

[drawing:piecewise]
answer = {x^2 : x < 0, 2*x : x >= 0};

Options

xmin, xmax, ymin, ymax

Bounds of the coordinate grid.

[drawing:function]
answer = x^2;
xmin = -5;
xmax = 5;
ymin = -2;
ymax = 25;

showgrid

  • true (default) — Display grid
  • false — Plain coordinate plane
[drawing:function]
answer = cos(x);
showgrid = true;
xmin = -2*pi;
xmax = 2*pi;

tolerance

Acceptable drawing error as a percentage of the visible area (default: 5%).

[drawing:function]
answer = x^3;
tolerance = 3;  // Stricter grading

Examples

Quadratic Function

$a = rand(-3, 3);
$b = rand(-3, 3);
$c = rand(-5, 5);

Draw the graph of `f(x) = $a*x^2 + $b*x + $c`.

[drawing:function]
answer = $a*x^2 + $b*x + $c;
xmin = -10;
xmax = 10;
ymin = -20;
ymax = 30;

Piecewise Function

Draw the graph of the piecewise function:

`f(x) = {x + 1 : x ≤ 0, x^2 : x > 0}`

[drawing:piecewise]
answer = {x + 1 : x <= 0, x^2 : x > 0};
xmin = -5;
xmax = 5;
ymin = -2;
ymax = 25;

Line with Specific Slope

$slope = rand(1, 3);
$yint = rand(-5, 5);

Draw a line with slope $slope and y-intercept $yint.

[drawing:line]
answer = $slope*x + $yint;
xmin = -10;
xmax = 10;
ymin = -20;
ymax = 20;

Solution Set on Number Line

Draw the point(s) that satisfy: `x = 2` and `y = -3`.

[drawing:point]
answer = (2, -3);
xmin = -5;
xmax = 5;
ymin = -5;
ymax = 5;

Grading

The system compares the student's drawing to the correct answer curve: - Matches within tolerance threshold → Correct - Differs by more than tolerance → Incorrect

Tolerance is calculated as a percentage of the visible coordinate area.

Tips

  • Use reasonable grid bounds: Too large or too small makes drawing difficult
  • Test the tolerance level: Adjust based on how precise your students should be
  • Provide context: Tell students what tools are available (Shift-click to add points, etc.)
  • Start simple: Introduce with linear functions before quadratics
  • Pair with calculator: Let students verify their answer using a graphing calculator first

Common Issues

  • Degenerate parabola: Very flat parabolas can appear as straight lines on large grids
  • Asymptotes: Functions with vertical asymptotes need careful grid bounds
  • Periodicity: Trigonometric functions need sufficient domain to show 1–2 complete cycles

See Also