Thank you for your views, ElaineR155! I agree with almost everything, but the 'big grin' is, I think, a defensive reaction to years of bewilderment with maths at school. Many people remember being humiliated by a maths teacher, with the other pupils laughing along, and some were of course physically punished. As you say, once you miss a vital part of the course you are sunk unless the teacher can help you catch up. I managed to get out of taking O-Level maths at my grammar school in the 1960s, feeling it was a waste of the time I should be spending on other subjects in which I had a better prospect of succeeding. We did a CSE course instead, and constructed a scale model of the school. I got a Grade 3, not worth the paper it was written on. (Incidentally, I scraped into Mensa many years later).