Passive voice makes is used in information reports and explanation texts to make writing sound more objective, impersonal, scientific technical, formal and official:

Formation

Active sentences focus on the subject: the person or agent performing the action.

The subject of the sentence (the doer) comes first:

Passive sentences focus on the object of the sentence and what happens to it.

The object of the sentence (the what) comes first , the verb "to be" (am/was/is/are/were/will) is added and the verb changes to a past participle (the verb form used when the word “have/has” comes before a verb) : 

aCTIVITIES