Count back & use the relationship between addition and subtraction to subtract within 20. Warm up with a Mystery Math Mistake to find the error in DC's addition. Use ...

Students put all of their addition and subtraction skills together to solve equations. In this lesson, students put all of their addition and subtraction skills together to solve equations. Julia ...

It’s no shocker that Harry and Hermione would know that 4 – 1 = 3. But what if I told you that this Harry and Hermione aren’t characters in Harry Potter stories — they’re stingrays. And they can still ...

When you are doing arithmetic by hand because your calculator’s batteries just gave up and your laptop is in the other room, it’s best if you can check your calculations with a different process than ...

Explains the concept of zero in mathematics, emphasizing its role as a number that represents the empty set. It illustrates how zero is used in addition and subtraction, showing that adding or ...

Some of the biggest challenges in teaching math aren’t about the numbers and operations themselves, but students’ attitudes toward them. Getting students to think deeply about problems, persevere ...