Students' socio-economic status explains 6.7% of the variation in familiarity with mathematics within the country. Around 70% of the students who have at least one tertiary educated parent reported that they know well or have often heard of the concept of linear equation, on average across OECD countries, only 52% of students whose parents have only primary education as their highest level of attainment so reported. Similarly, around 55% of students with highly educated parents and only 35% of students with low-educated parents reported that they know well or have frequently been exposed to the geometric concept of cosine.