You may just list the math, you may solve the math problems as they come up.
You might want to categorize.
At the end, be sure to ask “Has your definition of math changed?” and “What did you learn about math today?”
This will work with pretty much any story, so if you have a favourite, just go ahead and tell it. You may want to list some potential questions ahead of time in case you need to give gentle nudges.
subtraction, Smarties in box? for eyes? for buttons, how many used? how many left?
A woodcutter loses his axe in the river. A magical helper pulls out a silver axe and asks if it’s his. He says no. The magical helper pulls out a golden axe but the woodcutter will no take it. When he correctly identifies his humble axe, the magical creature allows him to keep all three as a reward for his honesty. In some versions others try to con the magical helper and lose their own axes.