Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.


Lesson Planning and Activity Resources

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1.NBT--Interactive games for Numbers & Operations in Base Ten

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First Grade Unit: Exploring Two-Digit Numbers(from North Carolina Dept. of Public Instruction)
This unit addresses 1.NBT.1, 2, 3, 5 and 1.OA.6.
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Grade 1 Unit: Understanding Place Value
(from Georgia Department of Education)
This unit addresses KCAS 1.NBT.2-6 and 1.MD.4.
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http://www.commoncoresheets.com/SortedByGrade.php?Sorted=1nbt5
Interactive Material find 10 more or 10 less than the number shown
Worksheets on finding ten more or ten less than a two digit number.

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Mental Math Resources
Link to Primary Resources site that includes power points and activites to demonstrate and practice mental math strategies.