The mathematics achievement test (MAT) comprising 10 unstructured questions that tested
knowledge, comprehension and application of all skills of the ‘scale drawing’ topic was used
in the study. The maximum score for the test was 70 marks. The instrument was validated by
five experts in mathematics education for face and content validity. Its reliability was
estimated to be 0.8402 Cronbach`s coefficient alpha. This was above the threshold of 0.7
which is considered suitable to make possible group predictions that are sufficiently accurate
(Gronlund, 1981).