Preheat oven to 300 degrees. Line a baking sheet with wax paper and set aside. Place pecans in a plastic bag and let the children beat them with a wooden spoon to break them into small pieces.
Place the vinegar in a mixing bowl (preferably a stand mixer), add the egg whites and a pinch of salt. Add 1 cup of sugar and beat the mixture on high for about 12 to 15 minutes or until stiff peaks form. Fold in the pecans.
Drop by spoonfuls onto the wax paper. Place cookie sheet in the oven, close the door and turn off the oven. Leave cookies in the oven overnight. They will cook from the residual heat.
Recipe by Nutritious Eats at https://www.nutritiouseats.com/cooking-with-kids-resurrection-cookies/