The highest grade completed is the last full grade completed, not the one in which the respondent is currently enrolled. For instance, if the respondent is currently enrolled in the third year of primary school, the highest grade completed is primary, 2 years. Post-secondary education refers to A-level and beyond. The first year of A-level counts as the first year of post-secondary education. Note that you must skip to question 7 after asking this question - you do not need to ask about reading, writing, and mathematical skills.