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 in a 21-part module has the class consider situations when it might be easier to add or subtract fractions by first converting to...
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.
Khan Academy
Khan Academy: Adding Two Digit Numbers (No Regrouping)
In this exercise, students practice adding two-digit numbers (no regrouping). Students receive immediate feedback and have the opportunity to get hints and try questions repeatedly.
Khan Academy
Khan Academy: Regrouping When Adding One Digit Numbers
In this exercise, students practice regrouping when adding one-digit numbers. Students receive immediate feedback and have the opportunity to get hints and try questions repeatedly.
Khan Academy
Khan Academy: Adding 1s or 10s (No Regrouping)
In this exercise, students practice adding 1s or 10s (no regrouping). Students receive immediate feedback and have the opportunity to get hints and try questions repeatedly.