British primary schools used to have something called ‘problem solving’ it was usually a simple maths problem described in words that required some degree of critical thinking to solve. e.g. A frog is at the bottom of a 30m well, it climbs 7m each day but in the night it slides 3m back down in its sleep. You can’t just calculate 30/(7-3) because it doesn’t account for the day the frog gets over the top and thus doesn’t slide back down in its sleep.

Not the most complex problem but pretty good for kids under 10 to start getting the basics.