The spare blade

Original non-fiction-style practice text.

The model-boat workshop kept a damaged propeller on the demonstration table. Its owner had brought it back after the boat began turning in circles. One blade had broken off, but the remaining ones still looked smooth. The tutor, Ines, used it during the first session of every course.

Learners compared it with a complete propeller and traced the missing shape onto paper. They could see why checking only the shiny surface would miss something important. Ines also showed a short recording of the boat before the part was changed. The object and the recording connected a visible defect with an observed change in performance.

The owner no longer needed the damaged piece, and it could not drive another boat. Ines asked permission to retain it rather than order a deliberately broken example. The workshop had enough perfect parts in their packets. This one helped explain a question which new learners were likely to meet once their boats left the table.

Give two teaching activities for which Ines uses the damaged propeller.