Spray baking sheet with a little cooking spray or rub a little butter all over it using a paper towel.
Put a strainer over a bowl. Measure flour, baking soda, baking powder and salt into strainer. Shake the dry ingredients into the bowl, trying hard to keep everything in the bowl.
ADULT: melt butter in the microwave or on the stove.
Crack egg into a small bowl. Carefully remove any egg shell.
In a 2-cup or larger measuring cup, measure the yogurt (to the ⅔ line). Add the egg and melted butter (have adult help if butter is still hot). Mix everything together with a whisk.
Make a hole in the middle of the flour mixture with a wooden spoon. Gently pour in the yogurt mixture. Stir until it is all completely mixed.
Sprinkle a little flour on the counter (or a cutting board or mat). Rub a little on your hands.
Put the dough on the counter and shape into a big flat circle with your hands. With a table knife cut a "peace sign" into the circle (all the way to the bottom). Then cut each of those pieces in half so you get 6 equal slices.
Put the pieces on the baking tray.
ADULT: Bake for approximately 15 minutes, remove from oven and put on cooling rack.
While the shortcake is baking, wash all of the fruit. If using strawberries, remove the green stem and cut into smaller pieces with the table knife. All of the other fruit is fine as it is.
Put the fruit in a bowl. Gently stir in the sugar. Let it sit to get syrupy with the shortcake bakes and cools.
Once they are cool, turn the shortcakes on their side and slice down the middle with the table knife. Put the shortcake on a plate, top with berries and yogurt (or whipped cream)