Dikes?

I was running the KS1 Level 3 Reading comprehension test. It was about the Netherlands. Non fiction text telling the children all about the Netherlands, dikes, flooding, windmills etc.

One of the questions was something like 'How did the villagers stop their village flooding?'

Child answered 'by having big dicks' (dikes)

She continued throughout the whole paper including the fiction part by talking about 'dicks'