One step, one mark.
Draw the diagram or write out your working, and get it marked point by point. Every mark comes with the reason it was given or lost, so you know exactly what to fix.
Opening soon with Economics, Business, Maths AA and Maths AI. The Economics question below already works.
How to draw
- Drag a curve to shift a copy of it. The original stays where it was.
- Choose “Mark a point”, then tap where two lines cross.
- Tap anything you drew to label it or delete it.
Shift demand or supply and mark the new equilibrium
The diagram shows the market for bus journeys, in equilibrium at P1 and Q1.
The government stops paying bus companies a subsidy for each journey they run.
Show the effect of this on the diagram, fully labelled.
Drag a curve to shift a copy. Tap what you drew to label or delete it. Arrow keys move it.
Text description of the diagram
- Title: The market for bus journeys
- Horizontal axis: "Quantity of bus journeys"
- Vertical axis: "Price of bus journeys"
- D1, falling line from (2.5, 8) to (8.5, 2), given
- S1, rising line from (2.5, 2) to (8.5, 8), given
- Point at (5.5, 5) with dashed lines to the axes, labelled P1 on the vertical axis and Q1 on the horizontal axis, given
Your marks go here, each with the reason it was given or lost.
Working is marked line by line.
Write one step per line. Each line gets its method (M), answer (A) or follow-through (ft) mark in the margin, with the rule it was marked against.
Find the equation of the tangent to y = x³ − 4x at the point where x = 2.
- 1dy/dx = 3x² − 4A1Correct derivative.
- 2gradient = 3(2)² − 4 = 8M1Puts x = 2 into the derivative.
- 3y = 2³ − 4(2) = 4A12³ − 4(2) = 8 − 8 = 0, so the point is (2, 0).
- 4y − 4 = 8(x − 2)M1Uses y − y₁ = m(x − x₁) with their point and gradient.
- 5y = 8x − 12A1 ftRight for their point (2, 4). From (2, 0) it would be y = 8x − 16.
Line 3 has a slip, so it loses one mark. Lines 4 and 5 use that wrong value correctly, so they keep theirs. That’s follow-through: one slip costs one mark, not the rest of the question.
4/5Every mark comes from a written rule that code checks, so the same answer always gets the same marks.