I discovered this extension today: 
https://chrome.google.com/webstore/detail/dualless/bgdpkilkheacbboffppjgceiplijhfpd?hl=en-GB

I only tried it out once today, but it gave options for different split screen sizes and was much easier than wrestling with tabs! 

Elisha

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Elisha Millerd Lewis
Library Media Specialist/Technology Integration 💻
Library Media Curriculum Specialist 📚
Portland Secondary Schools 
Portland, CT