Some cheeses stretch. Others don’t. Stretch your mind as you test cheese stretchability (and make grilled cheese sandwiches) in this edible experiment!
Place bread slices on cutting board. Sprinkle cheddar evenly over 1 slice of bread. Sprinkle mozzarella evenly over second slice of bread. Place 1 bread slice on top of each sandwich and press down gently.
In 12-inch nonstick skillet, melt butter over medium-low heat, swirling to evenly coat skillet, about 1 minute.
Place sandwiches in skillet and press down on them lightly with spatula. Cook sandwiches until first side is golden brown, 3 to 5 minutes.
Use spatula to flip sandwiches and press lightly again. Cook until second side is golden brown and cheese is melted, about 2 minutes.
Slide spatula completely underneath sandwich. Make sure spatula is large enough to hold sandwich.
Carefully place fingertips on top of sandwich. Lift spatula and flip sandwich over, moving your fingers out of the way as you flip sandwich onto second side. Repeat with remaining sandwich.
While sandwiches cool, make a prediction: Which cheese do you think will stretch more when you pull apart your sandwiches: cheddar or mozzarella?