The simple future tense is formed by using the helping (auxiliary) verb “will” with the main verb. The tense is used when there is no preconceived plan or thought, when there is a prediction made or when the verb “be” is used, even if there is a preconceived plan or thought. Consider the following examples:
Example 1: Maybe Barb will join the group (there is no plan, but it might happen).
Example 2: The sun will shine tomorrow (a prediction is made).
Example 3: She will be at the dance (the plan is made for her to attend the dance, but “be” is the main verb).