Illustrative Mathematics
Regrouping
What number does 6 tens and 16 ones represent? How is it different from or similar to the number that 7 tens and 6 ones represent? This is the type of questions learners are asked to solve as a way to understand the concept of regrouping.
Illustrative Mathematics
How Many Days Until Summer Vacation?
On the 124th day of school, young mathematicians are asked to find out how many days are left in the 180-day school year. The teacher version to the task offers several ways the problem can be solved, and can be used to guide...
EngageNY
Sums and Differences of Decimals
Sometimes dealing with decimals is so much easier than dealing with fractions. The ninth lesson plan in a 21-part module has the class consider situations when it might be easier to add or subtract fractions by first converting to...
Illustrative Mathematics
Ants Versus Humans
You would think that humans make up more mass than ants do on this planet, but think again, and this time by performing calculations. Middle schoolers use scientific notation to compute and compare the estimated total mass of all humans...
Khan Academy
Khan Academy: Add and Subtract Mixed Numbers (No Regrouping)
Practice adding and subtracting mixed numbers with common (like) denominators. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Regrouping: Two Digit Number Minus One Digit Number
In this exercise, students practice regrouping with two-digit number minus one-digit number. Students receive immediate feedback and have the opportunity to get hints and try questions repeatedly.