| Category | Name | Recoded Name | Description | Label | |
| 1 | Gender | ST004D01T | Gender | Student (Standardized) Gender | 1 - Female 2 - Male |
| 2 | Environmental | ST034Q06TA | Loneliness | I feel lonely at school. | 1 - Strongly agree 2 - Agree 3 - Disagree 4 - Strongly disagree |
| 3 | Environmental | ST265Q03JA | ClassroomSafety | Agree/disagree: I feel safe in my classrooms at school. | 1 - Strongly agree 2 - Agree 3 - Disagree 4 - Strongly disagree |
| 4 | Environmental | ST270Q03JA | TeacherSupport | How often: The teacher helps students with their learning. | 1 - Every lesson 2 - Most lessons 3 - Some lessons 4 - Never or almost never |
| 5 | School | STRATUM | SchoolType | Stratum ID 5-character (cnt + original stratum ID) | SGP01 - Public SGP03 - Private |
| 6 | School | ST296Q01JA, ST296Q02JA, ST296Q03JA | Homework_Math, Homework_Reading, Homework_Science | How much time spent on homework in: [Subject] homework | 1 - Up to 30 minutes a day, 2 - More than 30 minutes and up to 1 hour a day, 3 - More than 1 hour and up to 2 hours a day, 4 - More than 2 hours and up to 3 hours a day, 5 - More than 3 hours and up to 4 hours a day, 6 - More than 4 hours a day |
| 7 | Socioeconomic | HISCED | ParentsEducation | Highest level of education of parents (ISCED) | 1 - Less than ISCED Level 1 2 - ISCED level 1 3 - ISCED level 2 4 - ISCED level 3.3 5 - ISCED level 3.4 6 - ISCED level 4 7 - ISCED level 5 8 - ISCED level 6 9 - ISCED level 7 10 - ISCED level 8 |
| 8 | Socioeconomic | IMMIG | Immigration | Index on immigrant background (OECD definition) | 1 – Native Student 2 – 2nd Generation student 3 – 1st Generation student |
| 9 | Socioeconomic | ST022Q01TA | HomeLanguage | What language do you speak at home most of the time? | 1 - Language of test 2 - Other country 3 - I don’t know. |
| 10 | Socioeconomic | ST230Q01JA | Siblings | How many siblings (including brothers, sisters, step-brothers, and step-sisters) do you have? | 1 - None 2 - One 3 - Two 4 - Three or more |
| 11 | Socioeconomic | ST250D06JA | Aircon | Which of the following are in your home? <Air-conditioner> | 7020001 - Yes 7020002 - No |
| 12 | Socioeconomic | ST250D07JA | Helper | Which of the following are in your home? <Domestic helper (e.g. full/part-time maid)> | 7020001 - Yes 7020002 - No |
| 13 | Socioeconomic | ST251Q01JA | Vehicle | How many of these items are there at your home? Cars, vans, or trucks | 1 – None 2 – One 3 – Two 4 – Three or more |
| 14 | Socioeconomic | ST255Q01JA | Books | How many books are there in your home? | 1 - There are no books. 2 - 1-10 books 3 - 11-25 books 4 - 26-100 books 5 - 101-200 books 6 - 201-500 books 7 - More than 500 books |
| 15 | Wellbeing | EXERPRAC | Exercise | Exercise or practice a sport before or after school | 0 - No exercise or sports 1 - 1 time of exercising or sports per week 2 - 2 times of exercising or sports per week 3 - 3 times of exercising or sports per week 4 - 4 times of exercising or sports per week 5 - 5 times of exercising or sports per week 6 - 6 times of exercising or sports per week 7 - 7 times of exercising or sports per week 8 - 8 times of exercising or sports per week 9 - 9 times of exercising or sports per week 10 - 10 or more times of exercising or sports per week |
| 16 | Environment | ST250Q01JA | OwnRoom | Which of the following are in your [home]: A room of your own | 1 - Yes 2 - No |
| 17 | Environment | WORKHOME | FamilyCommitment | Working in household/take care of family members before or after school | 0 - No work in household or care of family members 1 - 1 time of working in household or caring for family members per week 2 - 2 times of working in household or caring for family members per week 3 - 3 times of working in household or caring for family members per week 4 - 4 times of working in household or caring for family members per week 5 - 5 times of working in household or caring for family members per week 6 - 6 times of working in household or caring for family members per week 7 - 7 times of working in household or caring for family members per week 8 - 8 times of working in household or caring for family members per week 9 - 9 times of working in household or caring for family members per week 10 - 10 or more times of working in household or caring for family members per week |
| 18 | Attitude | ST268Q01JA, ST268Q02JA, ST268Q03JA | Preference_Math, Preference_Reading, Preference_Science | Agree/disagree: [Subject] is one of my favourite subjects. | 1 - Strongly disagree 2 - Disagree 3 - Agree 4 - Strongly agree |