They take learners into more abstract language functions, such as giving and justifying opinions, speculation, and hypothesising.
Example
Asking ‘What colours make up a rainbow?' is an observational question, asking ‘Why are rainbows important?' is a higher question.
In the classroom
Amongst their many functions, higher order questions can be used to get learners to interpret things, suggest solutions to problems, explain why something is important, give opinions, and make comparisons. Learners need the opportunity to practise using language for these functions.
Further links:
https://www.teachingenglish.org.uk/article/asking-questions
https://www.teachingenglish.org.uk/article/storytelling-inclusive-practice-classroom