lesson
Test boundaries and failure paths
1 · Learn
A useful test specifies an input, expected result and actual result. Boundary tests probe the edges of permitted ranges. Invalid tests check whether bad input is rejected safely rather than silently accepted or causing a crash.
For ages permitted from 12 through 16 inclusive, test 11, 12, 16 and 17 as well as an ordinary valid value. Do not change the expected result after seeing the program's output merely to make the test pass.
2 · Worked example
12 and 16 should be accepted by the stated range, while 11 and 17 should be rejected.
3 · Your turn
Under that rule, should age 16 be accepted? Which nearby value tests just outside the upper boundary?
Check your answer
16 is accepted; 17 is just outside and should be rejected.
4 · Apply your learning
Create a test table before implementation and record a discovered defect with its smallest reproducing input.
Adult guidance and safety
Use an approved sandbox with invented data. Never ask for real passwords, personal records or access to another person's system. These text examples need executable projects and assessed evidence in two languages; reading code alone is not practical mastery.
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Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
Powers, roots and trigonometry · Year 7 onward
Use only when the task allows a calculator. Choose one operation at a time and record your working. Trigonometry here always uses degrees (DEG), not radians. Inverse sine, cosine and tangent return an angle, not a reciprocal. Keep exact fractions and π in answers when requested.
Approximate numerical results use up to 12 significant digits. Inverse sine returns −90° to 90°, inverse cosine 0° to 180°, and inverse tangent −90° to 90°; these are principal values, not every possible solution of a trigonometric equation.
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