My brown sugar always turns rock hard...

Try putting the sugar in a plastic container and microwaving it for 30 to 60 seconds. If it is still hard, add a couple of drops of water and microwave again. Or you can preheat your oven to 350 degrees F, then put the sugar in a pan and place it in the oven. Turn off the heat and let the sugar stand in the oven until it is soft. To prevent hardening in the future, try storing half an apple in a canister with the sugar.