Final answer:
Using slang words like 'cool' or 'rocked my world' in a school report is not acceptable. It is important to maintain a formal and academic tone in your writing to ensure credibility. If you are unsure about a word, consult a dictionary or thesaurus for more appropriate alternatives.
Step-by-step explanation:
The use of slang words such as 'cool' or 'rocked my world' in a school report is generally not appropriate. School reports are expected to be written in a formal and academic tone, using proper grammar and vocabulary. Slang words may be seen as unprofessional and can make the report less credible.
If you are unsure about a word you want to use, it is always best to consult a dictionary or thesaurus for alternative words that are more formal and suitable for an academic setting