IB Maths AI SL 2.1 - Lines Notes

This IB Maths AI SL 2.1 - Lines resource introduces straight lines, gradients, intercepts, and parallel and perpendicular lines, and is fully aligned with the IB Applications and Interpretation SL syllabus.

Students learn how straight lines can be represented graphically and algebraically, including how to use points on a graph to check whether a coordinate lies on a line. The notes introduce the y-intercept and x-intercept, helping students connect equations of lines with their graphical meaning.

The resource develops the concept of gradient as a measure of slope, using the rise-over-run formula between two points. Students learn how to calculate gradients from coordinates and interpret what the gradient tells them about the direction and steepness of a line.

The notes then introduce different forms of the equation of a straight line, including gradient-intercept form, general form, and point-gradient form. Students are encouraged to choose the most useful form depending on the information given in a problem.

Structured worked examples guide students through finding the equation of a line from two points, calculating the x-intercept, and interpreting intercepts as ordered pairs. The resource also explains how to identify parallel and perpendicular lines using their slopes.

The final section focuses on perpendicular lines, including how to find the opposite reciprocal gradient and form the equation of a new line through a given point. An exit ticket gives students a short opportunity to apply the lesson independently.

Ideal for IB Maths AI SL teachers teaching straight lines, gradient, intercepts, equations of lines, parallel lines, and perpendicular lines.

This pairs great with our slidedeck!