Adding and Subtracting Within 1,000
Visual cues aid advanced computation and extend learning.
TouchMath Second Grade Unit 3 presents adding and subtracting three-digit numbers. It begins with skip counting learned in the previous unit. This skill is then incorporated into a mixed review of adding and subtracting within 100, applying the concepts of operations with two-digit numbers. Extending the skill to include three-digit numbers transfers the learning at a more complex level. Understanding the place value is critical to success, students use visual cues to aid in computation. Composing and decomposing 100s or 10s in order to regroup is consistently reinforced. More complex comparisons and word problems are also included.
The unit closes with a review of multiplication. The learning is extended from unit three to having students find multiple ways to group objects and arrange them in arrays. The experiences in this unit provide the finishing touches with numbers and operations to the learning outcomes crafted by the Common Core State Standards.
Click the worksheet image to download free sample pages! One page per module is included for you to test in your classroom. NOTE: To preserve workspace for young learners and non-readers, and to provide lesson expansion opportunities, the page directions are included in the Instructional Strategies within each Module Guide.
This Unit includes:
- 150 student activity pages
- Implementation guide
- Six module guides complete with strategies and answer keys
- Pre-and Posttests for each module
- Three unique sets of FlipCards
- Adding and Subtracting Multiples of 10
- Adding and Subtracting Multiples of 100
- Representing Multiplication with Objects
- Access to digital content with TouchMath Green Editions
Need more FlipCards? Buy individual sets here!
Module 1: Adding and Subtracting Multiples of 10 and 100
The activities in this module are scaffolded from adding and subtracting multiples of 10 to/from 100 and then to/from each multiple of 100 in sequence. Skills are extended to adding and subtracting multiples of 10 within a three-digit number that is also a multiple of 10 (e.g., 540 + 40 and 580 - 40). The instruction then progresses to adding multiples of 10 to all three-digit numbers without regrouping (e.g., 649 + 30 and 679 - 30). The same process is used for adding and subtracting multiples of 100. Computation strategies (including doubles and number families) are reinforced, in/out tables provide practice in a variety of formats, and visual cues and word problems assist students throughout the activities.
Module 2: Adding and Subtracting Within 100
The activities in this module include practice with and without regrouping. The instruction focuses on using strategies both within operations and in problem solving. All strategies are presented with activities and visuals that have been previously presented to ensure that learners begin with what is familiar as they move into the more unfamiliar. For the computation strategies, instruction is presented to begin using the more familiar form of expanded notation through building 10. Number families, properties of operations, multiples of 10 (from the previous module), and multiples of 10 and 10 +/- 1 are implemented. Matching, finding pairs of addends that make a given sum, identifying addends that do and do not make a given sum, and flow charts are used to encourage student engagement.
Module 3: Adding Three-Digit Numbers
This module transfers learning from working within 100 to working within 1,000 using base 10 blocks to concretely demonstrate regrouping hundreds. Place value models and charts are used with the base 10 materials and then presented independently for visual support. Modified place value charts, indicators above the ones column, and boxes for the numbers regrouped are used to ensure learner success, and later eliminated as students gain experience and success. The complexity of the problems is scaffolded, beginning with regrouping only ones, then tens, then hundreds, and finally all digits. Students begin by adding a 1-digit number, then a 2-digit number, and finally a 3-digit number to a 3-digit number. Multiple addends are incorporated and new problem solving strategies are introduced: guess and check and write a number sentence.
Module 4: Subtracting Three-Digit Numbers
The activities in this module mirror those for addition in the previous module, reinforcing the understanding of place value throughout. Regrouping is extended to include zero and the visual cues are removed so that students internalize the process of subtracting. The use of unknowns in various positions continues to be used. Word problems are used extensively with two new problem-solving strategies introduced: use logic and estimate.
Module 5: Adding and Subtracting Three-Digit Numbers
Strategies from the two previous modules are used as students begin mixed practice, scaffolding the activities to increase the number of digits and the complexity of the problems. Students begin with no regrouping and move systematically to regrouping all digits. Unknowns in all positions and comparisons are continued as students progress to identifying part/whole relationships, drawing pictures, and applying the relationship of addition and subtraction. The importance of word problems is emphasized with two new strategies presented: work backward and choose a calculation.
Module 6: Reviewing Multiplication
This module extends and expands the introduction to multiplication presented in Unit 2, Module 4. Students start with identifying odd and even numbers by finding pairs. They then use pictures and numerals together as they begin the process before progressing to using the numerals independently. The activities then move to finding two equal addends, with all skills related to odd and even numbers. The symbol for multiplication is presented, and a soft introduction to the commutative property is included. Creating arrays up to five rows and five columns using pictures and then dots to represent problems is then scaffolded, with problems presented as addition of multiple addends and as multiplication. To conclude the module, students apply the learning in word problems, demonstrating understanding through drawing pictures and explaining the operation.