I do not agree with the statement "the school ‘s current policy should be changed to allow students to carry them".
Students should use cell phones for :
i. additional learning outside their school curriculum,
ii. developing skills via watching tutorials on online etc,
iii. developing research skills by finding relevant information. 
However, hardly few students use cell phones appropriately.The major chunk of students use mobiles in wrong ways, like, watching bad content, playing online games, passing time on social media. All such things decrease the productivity of the students & fill their mind with lot of un-necessary content.
Hence, I strongly feel, cell-phones should be banned in school. Also, their usage should be restricted at homes too. 
 
        
             
        
        
        
Answer:
The children sailed paper boats before dinner. 
Mothers call the children inside when dinner is ready. 
She fell while she was playing and injured her knee.
Explanation:
Prepositional phrases are composed at least of a preposition and an object. 
The word 'when' used as a conjunction means 'at the time that', and is followed by a subordinate clause. 
The word 'while' is used to connect two events occurring at the same time, and is followed by a subordinate clause. 
 
        
             
        
        
        
Sorry I need the full question
        
                    
             
        
        
        
Answer Togetherness?
Explanation:
Teamwork? Like the sum of one's parts?