Sub-goal A: Use non-count-by-one strategies to add or subtract a 1-digit number to or from a 2-digit number
Non-count-by-one strategies for adding or subtracting a 1-digit number to or from a 2-digit number involve applying knowledge of number relationships used for addition and subtraction in the range to 20 to higher decades. Tasks might stay within a decade family (76 + 3 or 56 – 4) or might require crossing a decuple (68 + 5 or 42 – 7). The instructional resources provide opportunities for students to apply strategies and basic fact knowledge to solve tasks in this extended range.
Home Communication and Engagement
Large Group
Instructional Activities
Adding To and Subtracting Down To a Decuple
Activity 6-A-L-1Purpose: Develop initial mental strategies for addition and subtraction involving adding on from a decuple and subtracting down to a decuple (e.g. 40 + 3 and 43 – x = 40)
Description: Students solve addition and subtraction tasks involving a 2-digit number and a 1-digit number. Tasks are presented on an empty number line, making connections to written equations.
Adding Up To and Subtracting Down From a Decuple
Activity 6-A-L-2Purpose: Develop initial mental strategies for addition and subtraction involving adding up to a decuple and subtraction down from a decuple (e.g. 37 + x = 40 and 40 - 3) while connecting knowledge of key combinations and partitions of 10
Description: Students solve addition and subtraction tasks involving a 2-digit number and a 1-digit number. Tasks are presented with a 100-bead string, making connections to written equations.
Adding and Subtracting Within a Decade
Activity 6-A-L-3Purpose: Develop initial mental strategies for addition and subtraction involving adding and subtracting within a decade (e.g. 43 + 5 and 48 – 3) while making connections to knowledge of structuring and relational knowledge to 10
Description: Students solve addition and subtraction tasks involving a 2-digit number and a 1-digit number. Tasks are presented with a 100-bead string, making connections to written equations.
Adding and Subtracting Across a Decuple
Activity 6-A-L-4Purpose: Develop initial mental strategies for addition and subtraction involving adding and subtracting across a decuple (e.g., 37 + 6 and 43 - 6) while making connections to knowledge of structuring and relational knowledge to 10
Description: Students solve addition and subtraction tasks involving a 2-digit number and a 1-digit number. Tasks are presented as a number string with the support of a 100-bead string.
Small Group
Instructional Activities
Adding To and Subtracting Down To a Decuple
Activity 6-A-S-1Purpose: Develop initial mental strategies for addition and subtraction involving adding on from a decuple and subtracting down to a decuple (e.g., 40 + 3 and 43 – x = 40)
Description: Students solve addition and subtraction tasks involving a 2-digit number and a 1-digit number. Tasks are presented with base-10 dot materials, making connections to written equations.
Adding Up To and Subtracting Down From a Decuple
Activity 6-A-S-2Purpose: Develop initial mental strategies for addition and subtraction involving adding up to a decuple and subtracting down from a decuple (e.g., 37 + x = 40 and 40 - 3) while connecting knowledge of key combinations and partitions of 10
Description: Students solve addition and subtraction tasks involving a 2-digit number and a 1-digit number. Tasks are presented with Mini 10-frames, making connections to written equations.
Adding and Subtracting Within a Decade
Activity 6-A-S-3Purpose: Develop initial mental strategies for addition and subtraction involving adding and subtracting within a decade (e.g., 43 + 5 and 48 – 3) while making connections to knowledge of structuring and relational knowledge to 10
Description: Students solve addition and subtraction tasks involving a 2-digit number and a 1-digit number. Tasks are presented with Mini 10-frames, making connections to written equations.
Adding and Subtracting Across a Decuple
Activity 6-A-S-4Purpose: Develop initial mental strategies for addition and subtraction involving adding and subtracting across a decuple (e.g., 37 + 6 and 43 - 6) while making connections to knowledge of structuring and relational knowledge to 10
Description: Students solve addition and subtraction tasks involving a 2-digit number and a 1-digit number. Tasks are presented as a number string with the support of Mini 10-frames.
Independent
Instructional Activities
Ultimate Tic-Tac-Toe
Activity 6-A-I-1Purpose: Develop initial mental strategies for addition involving adding on from a decuple (e.g., 40 + 3)
Description: Students solve addition tasks, trying to get three in a row in a traditional game of Tic-Tac-Toe.
Climb the Mountain
Activity 6-A-I-2Purpose: Develop initial mental strategies for subtraction involving subtracting down to a decuple (e.g., 43 – x = 40)
Description: Students solve subtraction tasks, completing a sequence of four.
Adding to Get
Activity 6-A-I-3Purpose: Develop initial mental strategies for addition when adding up to a decuple (e.g., 37 + x = 40)
Description: Students attempt to get four counters in a row by adding to a decuple.
Take Off
Activity 6-A-I-4Purpose: Develop initial mental strategies for subtraction involving subtracting down from a decuple (e.g., 40 – 3) connecting to knowledge of key combinations and partitions of 10
Description: Students spin to determine what they will subtract from a decuple to get four counters in a row.
Find Four
Activity 6-A-I-5Purpose: Develop initial mental strategies for addition and subtraction involving adding and subtracting within a decade (e.g., 43 + 5 and 48- 3)
Description: Students apply structuring knowledge to solve addition or subtraction tasks within a decade, while trying to make a sequence of four on an activity board.
Five In a Row
Activity 6-A-I-6Purpose: Develop initial mental strategies for addition and subtraction involving adding and subtracting across a decuple (e.g., 37 + 6 and 43 - 6)
Description: Students apply knowledge of structuring to solve addition and subtraction tasks, attempting to make a sequence of 5 on an activity board.
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