Here is a part-whole model. Sometimes the model is rotated. It looks different, but it still has two parts and a whole. We can use this model to help us solve problems. We can put 4 things in one of ...

Practice adding and subtracting within 20 using a Double 10-frame & number line. Represent a teen number using a number bond to solve a Mystery Math Mistake. Use Notice and Wonder with a marble game ...

Stingrays and zebra mbuna fish can perform simple addition and subtraction involving numbers between 1 and 5. Several studies have shown that fish can tell the difference between higher and lower ...

The common-core math standards require that students learn the standard algorithm for multi-digit adding and subtracting—you know, the process in which you line the numbers up vertically to add or ...