He sent a postcard to his brother. The noun receiving the direct object is the indirect object. After class, Randall will give the students their papers . Once you identify the verb, ask whether the verb was done to someone or something. Yes, he will give papers.
Students is the indirect object.
Identify the subject, find the verb the subject is engaged in, determine if it is an action verb, ask who or what is receiving the action and then ask who or what is receiving that object.