To fold a blanket, it helps to have two people. Age and skill are not required as along as you are at least tall enough not to drag it on the floor. Seven or eight is old enough. If you have an older sister, chances are good she will be assigned to blanket folding with you.
With plenty of grumbling that you’ve been tasked with anything at all and some lingering animosity for something the two of you fought about earlier, begin.
First, with you at one side and your sister at the other, grab your two corners of the blanket, pulling them together to meet. Now grab both corners with your left hand while she grabs hers with her right. In sync, reach down for the fold you just created. Bring your hands to meet a second time, creating a long thin rectangle. Gently shake it to smooth it out, unless you’re still angry. Then whip it like mad till she loses her side and yells, while you primly say, “I was just trying to get out the wrinkles.”
Once she retrieves her end, walk together, arms held high, to meet in the middle. Since you made her drop her edge, she may make you walk all the way to her. Give her your corners and bend to pick up the bottom edge. Hand that to her as well. She will set the bundle down and smooth it with her hand.
Then begin again with the sheets. Fold so many so often over the years, that you both move easily in line. The task goes quickly and you smile across at each other.
Now that you have the process down, you can partner with your spouse, daughters, even friends on occasion, but you never quite achieve that synchronicity, that almost psychic sense of where she is going to move next.
Now miles and lives apart, you never lose the trust that she will hold up her end for as long as you need it.