premise: batteries convert chemical energy to electrical energy sent2: a flashlight is a kind of electrical device sent3: a kind of is similar to a form of sent4: a flashlight emits light sent5: electrical devices convert from electrical energy  into other forms of energy sent6: a flashlight is a kind of battery-operated device sent7: light is a kind of energy sent8: battery is the source of electrical energy for battery-operated device.
hypothesis: plants increase the amount of oxygen