One of my enduring memories of my dad is the afternoon he taught me All Silver Tea Cups. I was may be in Class 5 and trignometry was far away in Class 10. He was younger than I am now and I was older than my kids are now. I remember him pulling out a rough note book, drawing the four quadrants and explaining the mnemonic to me. I was too young to grasp it but the mnemonic stayed with me and the memory. Sometimes I wonder if any of the random info dumps I do to my kids end up as a core memory like ASTC.