The principal of an online high school is broadening the conversation about children's screen time.  

In an article in today's Medical Journal a group of experts calls for breaks, the use of blinking exercises, more hearing and visions tests for children, and more research on the dangers of screens.  

But Mark Phillips, Principal of online high school Crimson Global Academy, told Mike Hosking the time spent on screens isn't the primary concern.   

He believes it's more about the content a child is watching on the screen, rather than how long they're doing it. 

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