In Module 4, Topic A, students build upon their understanding of the base ten system and their prior knowledge of place value strategies presented in Module 3. In Lesson 1, students relate 10 more and 10 less and 1 more and 1 less to addition and subtraction. They recognize that they must add and subtract like units and that the digit in the tens place changes when adding and subtracting 10, just as the digit in the ones place changes when adding or subtracting 1. Students see numbers in terms of place value units; 54 – 10 is 5 tens 4 ones minus 1 ten. They learn to record the addition and subtraction of multiples of 10 using arrow notation. In Lesson 2, students apply place value understanding to add and subtract multiples of 10 before counting on by tens. For example, when adding 20 to 43, they may count 53, 63. Students also develop flexibility in using related addition problems. For example, to solve 92 – 60, one student might think 9 tens – 6 tens is 3 tens, plus 2 is 32, while another starts at 60, adds on 3 tens, and then 2 ones to reach 92, so 32.

Content Standard(s):

Mathematics MA2019 (2019) Grade: 2

1. Use addition and subtraction within 100 to solve one- and two-step word problems by using drawings and equations with a symbol for the unknown number to represent the problem.

Unpacked Content

Evidence Of Student Attainment:

Students:

solve a variety of addition and subtraction problems, using concrete and pictorial representations.

explain and justify solutions using connections among a variety of representations (e.g., manipulatives, drawings, and equations with a symbol for the unknown number).

write equations that represent the work they have shown.

Teacher Vocabulary:

One-step word problems

Two-step word problems

Knowledge:

Students know:

addition and subtraction strategies to solve one- and two-step word problems within a 100.

Skills:

Students are able to:

represent quantities and operations (addition & subtraction) physically, pictorially, or symbolically.

strategically use a variety of representations to solve addition and subtraction word problem.

use informal and mathematical language to communicate the connections among addition and subtraction.

accurately compute sums and differences.

use symbols to represent unknown quantities in equations.

Understanding:

Students understand that:

addition is both putting together and adding to.

subtraction is taking apart, taking from, and comparisons.

mathematical problems can be solved using a variety of strategies, models, representations.

variables represent unknown quantities when representing mathematical situations algebraically.

Diverse Learning Needs:

Essential Skills:

Learning Objectives: M.2.1.1: Solve one-step addition and subtraction word problems with an unknown by using drawings and equations with a symbol for the unknown number to represent the problem.
M.2.1.2: Understand key words in addition and subtraction word problems.
Examples: adding to, taking from, putting together, taking apart, sum, difference, all together, how many more, how many are left, in all.
M.2.1.3: Locate the unknown regardless of position.
Examples: start unknown, change unknown, and result unknown.
M.2.1.4: Apply signs +, -, = to actions of joining and separating sets.
M.2.1.5: Add and subtract within 50, e.g., by using objects or drawings to represent the problem.
M.2.1.6: Solve addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects or drawings to represent the problem.
M.2.1.7: Represent addition and subtraction with objects, fingers, mental images, drawings, sounds, acting out situations, verbal explanations, expressions, or equations.
M.2.1.8: Represent numbers with objects or drawings.

Prior Knowledge Skills:

Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using objects or drawings to represent the problem.

Understand key words in addition and subtraction word problems. Examples: sum, difference, all together, how many more, how many are left, in all.

Define subtraction as separating groups of objects, taking from, or taking apart.

Define addition as combining groups of objects, adding to, or putting together.

Represent addition and subtraction with objects, fingers, mental images, drawings, sounds, acting out situations, verbal explanations, expressions, or equations.

Represent numbers with objects or drawings.

Use objects to combine and separate groups.

Define how many, all together, and in all.

Count to 20 by ones.

Demonstrate 1:1 correspondence.

Mimic counting objects in sequential order arranged in a line, circle, or array.

Count no more than 5 objects in a scattered configuration.

Mimic counting no more than 5 objects in a scattered configuration.

Count to 10 by ones.

Count in sequential order.

Mimic counting in sequential order.

Demonstrate one to one correspondence.

Make purposeful marks such as lines and circles.

Mathematics MA2019 (2019) Grade: 2

10. Fluently add and subtract within 100, using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

Unpacked Content

Evidence Of Student Attainment:

Students:

solve addition examples with sums to 100 using a variety of strategies.

solve subtraction examples with differences within 100 using a variety of strategies.

justify solutions and explain the reasoning for the strategy chosen.

Teacher Vocabulary:

Properties of operations

Knowledge:

Students know:

strategies and methods for symbolically (numerically) recording strategies for fluently solving addition and subtraction problems.

Skills:

Students are able to:

record strategies for solving addition and subtraction problems.

communicate the relationship between models and symbolic (numeric) representations of solutions to addition and subtraction problems.

Understanding:

Students understand that:

models/strategies can be used to justify their answers.

Diverse Learning Needs:

Essential Skills:

Learning Objectives: M.2.10.1: Add within 100, including adding a two-digit number and a one-digit number and adding two two-digit numbers, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method, and explain the reasoning used.
M.2.10.2: Add within 20, demonstrating fluency for addition within 10. Use strategies such as counting on; making ten; decomposing a number leading to a ten; and creating equivalent but easier or known sums.
M.2.10.3: Determine the value of the number in the ones, tens and hundreds place.
M.2.10.4: Model written method for recording horizontal and vertical addition problems.
M.2.10.5: Understand that the two digits of a two-digit number represent amounts of tens and ones.
M.2.10.6: Match the number in the ones and tens position to a pictorial representation or manipulative of the value.

Prior Knowledge Skills:

Notice same/different and some/all.

Subtract one from a set of objects (up to 10 objects).

Given a group of objects (20 or less), divide the group into smaller groups in various ways.

Take away objects from a large group to create two smaller groups.

Establish one-to-one correspondence between numbers and objects when given a picture a drawing or objects.

Understand number words.

Understand that 10 1's = 10.

Count forward to 100 by tens.

Count backwards from 100 by tens.

Mimic counting to 100 by tens.

Recognize numbers from 1-100.

Become interested in how many objects she/he has.

Understand the concept of size and amount.

Given a set number of objects one through ten, answer the question "How many?"

Pair the number of objects counted with "how many".

Alabama Alternate Achievement Standards

AAS Standard: M.AAS.2.10 Using vocalization, sign language, augmentative communication, or assistive technology, identify the meaning of the + sign (add, plus, put together) and the sign (subtract, take away, take from) and the = sign (equal, the same as); compose and decompose numbers up to 20 using objects, pictures, drawings, or numbers.

Mathematics MA2019 (2019) Grade: 2

13. Mentally add and subtract 10 or 100 to a given number between 100 and 900.

Unpacked Content

Evidence Of Student Attainment:

Students:

Use a variety of materials and strategies to add or subtract 10 or 100 from a three-digit number in the range of 100 to 900.

Knowledge:

Students know:

use place value models for adding and subtracting numbers from 1 to 1000.

use strategies for mentally adding and subtracting multiples of 10 and 100.

Skills:

Students are able to:

use patterns and regularity in counting sequences and understandings of place value to add or subtract a "ten" or a "hundred".

communicate reasoning and solution strategies.

Understanding:

Students understand that:

the digits of a 3-digit number represent amounts of hundreds, tens and ones.

patterns in the place value system can be used to mentally compute sums and differences.

Diverse Learning Needs:

Essential Skills:

Learning Objectives: M. 2.13.1: Demonstrate conceptual understanding of adding or subtracting 10 using concrete models.
M.2.13.2: Recognize the place value of ones, tens and hundreds.
M.2.13.3: Count forward and backward by 100.
M.2.13.4: Count forward and backward by 10.
M.2.13.5: Recall single-digit subtraction facts.
M.2.13.6: Recall single-digit addition facts.

Prior Knowledge Skills:

Recognize numerals from 1-50.

Become interested in how many objects she/he has.

Understand the concept of size and amount.

Given a set number of objects one through ten, answer the question "how many?"

Pair the number of objects counted with "how many?"

Understand that the last number name tells the number of objects counted.

Understand that 10 1's = 10.

Establish one-to-one correspondence between numbers and objects when given a picture, a drawing or objects.

Pair a group of objects with a number representing the total number of objects in the group.

Count objects one-by-one using only one number per object.

Recognize that numbers and numerals have meaning.

Mimic counting forward and backward by 100.

Mimic counting forward and backward by 10.

Communicate number words.

Recognize after.

Recognize before.

Understand one less than a number 2 through 20.

Understand one more than a number 1 through 20.

Tags:

10, 100, addition, mental math, operations, place value, subtraction, word problems