A teacher has 21 red pens. If the ratio of red pens to blue pens she owned was 3:1, how many pens did she have total? It’s one of the word problems sixth-graders at Vera C. O’Leary Middle School were ...

*Refers to the latest 2 years of stltoday.com stories. Cancel anytime. Back-to-school time is officially upon us, and by now everyone has seen a Common Core math problem that takes something simple ...