How can you tell if a reaction is endothermic or exothermic? Describe a way of determining if a reaction is exothermic or endothermic using simple laboratory equipment.

Exothermic and Endothermic reactions refer to if the change in Enthalpy of a reaction is negative or positive respectively.
If a reaction is exothermic that means that enthalpy change is negative and heat is released due to the fact that there is less energy(enthalpy) contained within the products than the reactants. Conversely, if a reaction is endothermic, the enthalpy change is positive and heat is absorbed because the products now have more energy(enthalpy) than the reactants.

A thermometer could be used to track if a reaction produced heat (exothermic) or absorbed heat (endothermic). A specialised piece of equipment called a calorimeter is used to accurately calculate enthalpy changes in a reaction using a similar method.