2 Answers

What kind of school report? This is kind of vague.

BASICALLY, since you do not give a topic, grade level, or any other information, a SCHOOL REPORT should have

1. Introductory paragraph, in which the topic is indicated by way of anecdote, question, or exclamatory statement (as opposed to: This report is about blah blah blah)

2. Paragraphs (5-7 cohesive sentences) that progress logically and/or chronologically through the information or timeline the report needs to cover.

3. Closing paragraph, which summarizes the information by highlighting the most important points. The ending sentence can be humorous, a closing question, or a simple statement that sews up the topic. 

Example: My son once wrote a report about potatoes.  He started out by asking a riddle, the answer to which was "POTATO".  
In the body of paragraphs, he discussed how and where potatoes are grown, followed by the nutritional value of potatoes, followed by the Irish potato famine.  He enumerated the many different kinds of potatoes, giving a common use for each one.
His closing paragraph reiterated the importance of potatoes as a crop (3-4 main points), and reminded the readers of the many varieties of potatoes.
The closing sentence was in reference to the inedible potato: the COUCH potato.

He got an A.  It was 3rd grade.