I vaguely remember decimalisation. We had a toy cash register (like this one from Casdon https://i.ebayimg.com/images/g/w70AAeSw47RowXOf/s-l1600.jpg) with plastic coins so we could learn to add with new money, but since I was too young to know how to add with old money, that didn’t really make a difference. We just used the old coins for setting off caps from cap guns, and I still have the burn on my thumb all these decades later.

As far as I was I was concerned the big change in class was going from plasticine to Cuisenaire Rods.