Heat the oven according to the cake-mix package directions, usually 350°F. Grease a 9-by-13-inch baking pan, prepare the white cake batter with 3 eggs, 1/3 cup vegetable oil, and 1 cup water as directed on the package, then pour the batter into the prepared pan.

Bake the cake for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean. Let it cool in the pan for about 10 to 15 minutes so it is warm but no longer piping hot.

Use the handle of a wooden spoon, a skewer, or a large drinking straw to make evenly spaced holes about 1 inch apart across the cake. Choose a wider tool so the gelatin can travel into the crumb without tearing the cake.

Place the strawberry gelatin in a bowl and stir in 1 cup boiling water until the crystals dissolve completely. Stir in 1/2 cup cold water to cool and dilute the mixture.

Slowly pour the gelatin over the warm cake, moving across the surface so it reaches as many holes as possible. Pause briefly if needed to let the liquid absorb instead of pooling heavily in one area.

Refrigerate the cake for at least 1 hour, or until it is completely chilled and the gelatin is set. The cold cake will be firmer and easier to cover without melting the whipped topping.

Spread the thawed whipped topping evenly over the chilled cake. Arrange the hulled and sliced strawberries over the topping, then refrigerate until serving.