Roy Ehrlick, a former colleague at IS 143 in Manhattan who passed away earlier this fall, was the most selfless person I have ever known. He was a teacher 24 hours a day and available to students 365 days a year.

My compliments to Christina Gavin, the Herbert H. Lehman HS Campus librarian featured in the Sept. 5 “What I Do” column.

The terrible shooting at an El Paso, Texas, shopping mall is yet another reminder that there are far too many people in this country who are mentally imbalanced and should never own a weapon.

President Trump tells people to go back where they came from for being critical of the U.S — this coming from a man who has been very critical of American policies and Americans both before and after coming into office. (The words “American carnage” come to mind.)

In 2014, while my kindergarten students at PS 290 in Manhattan were doing research about tomatoes and other foods in our cafeteria, they learned about pesticides. They did role-plays where farmworkers or gardeners were coughing and rubbing the rashes caused by the (pretend) pesticides sprayed on the tomatoes.

Good luck to all the new teachers joining the profession! Remember that the union is only as strong as its members.

My recent letter concerning Elizabeth Warren’s advocacy for relieving students of their college debt, whereby I suggested that students be required to perform public service in exchange for such relief, produced some provocative responses.

And now, our esteemed mayor, Bill de Blasio, is running for president of the United States! 

The article “Civics Education” [Learning Curve column, June 6], mistakenly refers to “American democracy.” Of course, the United States was founded as a constitutional republic, not as a democracy. 

I’m one of those who went out on strike and lost two days’ pay for each day on strike. However, I took my entire department out with me, including a nonmember of the union. I have fond memories of that woman and that strike.