Erratum

The original article [1] contained an error whereby Fig. 2a and b were mistakenly swapped with each other, and thus did not correspond to their correct respective sub-figures. The original article has been updated to include the correct configuration of Fig. 2a and b which can also be viewed ahead.

Fig. 2
figure 1

Different types of online questionnaires. a Embedded answers (gap fill). b matching. c true/false, multiple choice and matching tests