Challenge students to estimate and record their answers first, and then use a 'Numberless Protractor' to measure each angle, calculate the error.
Using a timer will create some 'urgency' for students to complete the task quickly. IWB software has built-in protractors (typically, a traditional protractor) and the Maths 300 lesson Angle Estimation has some some useful software.

Numberless Protractorsreasonableness of answer' approach to measuring angleslots of 10' and then estimate the last part of an angleAngle Estimation sheetChallenge students to estimate and record their answers first, and then use a 'Numberless Protractor' to measure each angle, calculate the error.

Using a timer will create some 'urgency' for students to complete the task quickly. IWB software has built-in protractors (typically, a traditional protractor) and the Maths 300 lesson Angle Estimation has some some useful software.