Roll 3d6, assign as you wish.
STRENGTH: How strong you are. Useful for fighting, climbing, and carrying treasure.
+/- to melee attack and damage
DEXTERITY: How fast you are and how accurate your aim is.
+/- to ranged attack and Armor Class.
CONSTITUTION: How healthy you are.
+/- to Hit Points
INTELLIGENCE: How much you know, and how good you are at figuring things out.
+/- to Spells learned with leveling as a spell-caster
WISDOM: How aware you are of the world around you, including the spirit world.
+/- 10% XP
CHARISMA: How good a leader you are, and how well you can get along with people and animals.
Add up all your attributes to determine how many Luck Points you have.
78 or more 0
You can spend a Luck Point to automatically succeed at a roll. Luck points are refreshed between adventures. Success from spending a Luck point should be narrated as fortuitous happenstance that comes out of character incompetence, à la Inspector Clouseau.
I use attribute checks when playing with the kid, even though I'm becoming pretty disenchanted by them in my regular games. It's a straight-forward, flexible mechanic that use the most prominent numbers on the character sheet—ideal for the Kid's Game.
I had developed a very simple skill system for the Kid's Game, but I think I'm going to ditch it in favor of just using attributes. If you want to sneak, it's a DEX check, not a separate skill. But, this means that if there are opportunities for skill advancement, this will be done by improving attributes numbers, which is a pretty big departure from the game I'm trying to scaffold.
It is fascinating watching the kid recreate so much of the history of old school rule-hackery. He pointed out the possibility of an Ascending Armor Class the first time he saw the attack matrix (although, proto-grognard that he is, he then insisted on using Descending), and has been reinventing a lot of the old familiar schemes for getting better character stats: roll 3d6 seven times, drop lowest; roll four characters, keep best; etc.
I'd much rather add a mechanic that grants utility to characters with low stats than reconjigger chargen to produce higher stats, like 4d6-drop-lowest. Weaknesses lead to more interesting characters, more interesting play, and better teamwork.
The Luck mechanic is my solution, but it needs more playtesting. It's obviously something that would be considered game-wrecking in the regular game, but young kids need some get-out-of-jail free cards.
Or, at least, my kid does. Holy Geez, it is terrifying to discover just how unhinged my kid's problem-solving skills are. A typical example: To stop a run-away wagon, he rides his horse up and leaps onto the wagon. But, instead of grabbing the reins of the bolting horses, he takes his bow and shots his sword at a tree, hoping to chop it down and block the wagon's path.
It was pretty amazing, actually.