This argumentative writing activity (CER = Claim, Evidence, Reasoning) is centered on an interesting question: Why is Bill Gates so interested in toilets?The (shortened) backstory is that 2.6 billion people in the world don't have sanitary toilets, which leads to contamination, illness, and malnutrition. Bill Gates launched a challenge to reinvent the toilet for cities and villages that don't have modern plumbing systems. Links to several videos are included to share with your students. Click h