This is apparently how kids are being taught subtraction.
Via DC:
Here is the latest in the never-ending litany of frighteningly stupid Common Core math worksheets. This one comes from the father of a kindergarten student in the Research Triangle area of North Carolina.
“I have a Ph.D., and I have no idea what is supposed to be done with this homework assignment,” the flummoxed father told The Daily Caller.
He sent the bizarre worksheet to TheDC on the condition of anonymity because he didn’t want to risk having his child be the subject of any reprisals from school employees.
The doctoral dad added that he did research some of the terms on the worksheet “enough to know that ‘K.OA.1′ is Common Core language.” (TheDC’s cursory Google search of the term ‘K.OA.1′ brought up “Kindergarten Common Core Math” with the second hit.)