Community-created
The Big Trade: Adding When the Ones Spill Over
by Autumn-Field-45794A hands-on series for 2nd graders on adding two-digit numbers when the ones add up past 9. Learners discover why ten ones must be traded for one ten, connect that trade to the written method, and pick up mental strategies and ways to check their own answers.
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Lesson 1
The Ones Box Is Full!
Sam added 27 + 15 and got 312, and every little sum he did along the way checks out, so where exactly did the answer go so wildly wrong?
StartLesson 2
Twelve Dots, One Tiny Box
Sam's 27 + 15 left 12 dots crammed into a box built for 9, and not a single dot can be thrown away, so how do you make them all fit?
StartLesson 3
The Little 1 on Top
Grown-ups write a tiny 1 above the tens when they add. What does it stand for, and why does it go there?
Locked till you take the prior lessonLesson 4
Tens First, Then Ones
What if you added the big parts first? Break numbers apart and discover a second way to add that always works.
Locked till you take the prior lessonLesson 5
Friendly Number Tricks
39 + 24 is annoying. 40 + 23 is easy. Learn how to give and take to make hard sums friendly.
Locked till you take the prior lessonLesson 6
Does That Answer Make Sense?
Become an answer detective. Learn to spot wrong answers fast and check your own work before anyone else does.
Locked till you take the prior lessonLesson 7
When the Tens Spill Over Too
What happens when the tens get too full as well? Find out where all those tens go.
Locked till you take the prior lessonLesson 8
Story Problems: Pick Your Tool
Real problems about pencils, points, and pennies. Choose the best adding strategy for each one and explain why.
Locked till you take the prior lesson