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