A good topic for children is a turtle like in Logo. Make some nice drawings. Make smalls programs so you can repeat the drawings. Parameterize the function, so you can change the size of the drawings. Perhaps add some other tweaks, like customizable colors, or optional parts. Bonus points for making the turtle return to the original position and direction. Extra bonus points for understanding why that is useful.
Another good topic is solving recreational math problems. Some problems involve equations with small integer numbers and if they can nest a few `for`s and `if`s then they can bruteforce the solution. Bonus point for discussing the bounds, to ensure that all the options are considered. Extra bonus point for an informal idea of the complexity of the program, and guessing if it will finish instantly, after a wile, or never.
[1] I'd teach Fibonacci for kids if I were teaching them Excel, because you can see the whole sequence. Excel is a very powerful tool and is a gateway to programing. Remember to tech you kids Excel. (Not VBA, just plain cells, lot's of cells.)