This is a good way to get students to think not just about what a good answer will include, but the range of possible good answers. When they have to put themselves in the position of examiner, students can begin to develop better habits as they think about how their own answers will be received.
An example is shown below (full version here). Each question has two boxes below it, one for the mark scheme and one for the answer. It helps to have one question done for the students first. I ask students to do both at the same time, but you could vary it by asking them to just do one side and have another student complete the other, then return to the original person for further discussion.
Describe the expected growth in tourism between 2010 and 2030. 
|Overall growth 
Any two appropriate points for remaining marks such as:
All regions experience growth 
Biggest growth in Asia 
Smallest amount remains in Africa 
Largest amount remains in Europe 
Smallest rate of growth in Europe 
Must have quantifiation for full marks. No quantification allow max 2 marks.
|There is predicted to be a growth in international tourism in all regions, with the greatest rate of increase in Asia from 200m in 2010 to over 500m in 2030. However, the greatest total will remain in Europe with an increase of just 150m taking the total to 650m by 2030. Africa remains the smallest contributor despite an increase of over 50m.|
Identify three impacts this is likely to have on the world economy. 
To prepare, make sure students have done a few practice tests and have access to the mark schemes. This is essential, otherwise students won’t have enough exam awareness of build on. I use the questions on this site as the source for these, and always provide the students with the link to the relevant page so they can see the various possible answers to the questions.
The most important aspect of a lesson like this is to monitor the student responses to check the mark schemes that are being written are on the right lines. It’s a great way of seeing what they expect a good answer to look like – and allows for quick and early detection of any misconceptions about what the mark scheme is looking for.