First put your gummy bears in a bowl. You want to microwave gummy bears in 10 second increments stirring in between until they are a thick liquid. Carefully remove and add your corn starch and 1 tsp of powdered sugar.
Continue adding 1 tsp. of sugar at a time stirring every time you add more until it becomes less sticky and cools down.
Continue stirring the mixture. Stop once you reach the consistency you think will be good. Allow it to cool down enough to pick it up and knead it, this may take a while but keep an eye on it so it doesn't harden into a big ball.
Once cooled, sprinkle powdered sugar on to your paper plate and dump edible slime on to plate or play mat. Knead and play with it as you see her doing. The powdered sugar will help prevent sticking but make sure they aren't wearing really nice clothing when making this in case it gets on it, doesn't come off well.