The 13-year-olds who took the basic skills tests were fourth and fifth graders when the pandemic struck, and the disruption at that point in their schooling appears to have been particularly damaging.

What’s the viral math equation? READER'S DIGEST, GETTY IMAGES. You’ve no doubt seen this math problem (or one similar to it) making the rounds on Facebook: 4×4-4÷4+4. The equation seems so ...