Unit 4

Place Value, Comparison, Addition and Subtraction to 40

 

Grade 1

Math

 

 

Description: Students build understanding of place value. Addition and subtraction within 40 rest primarily on establishing a “ten” as a unit that can be counted. Students begin to see a problem like 23 + 6 as an opportunity separate the “2 tens” in 23 and concentrate on the familiar addition problem 3 + 6. Adding 8 + 5 is related to solving 28 + 5; complete a unit of ten and add 3 more.

Louisiana Student Standards for Mathematics (LSSM)

Instructional Outcomes

 

Numbers and Operations in Base Ten

Represent and solve problems involving addition and subtraction.

1.OA.1

 

 

Use 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, drawings, and equations with a symbol for the unknown number to represent the problem.

Extend the counting sequence.

1.NBT.1

 

 

Count to 120, starting at any number less than 120.  In this range, read and write numerals and represent a number of objects with a written numeral.

Understand place value.

1.NBT.2

 

 

Understand that the two digits of a two-digit number represent amounts of tens and ones. 

1.NBT.3

 

 

Compare two two-digit numbers based on meaning of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <.

Use place value understanding and properties of operations to add and subtract.

1.NBT.4

 

 

Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10.

a. Use 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 number sentence; justify the reasoning used with a written explanation.

b. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

1.NBT.5

 

 

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

1.NBT.6

 

 

 

Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero difference), 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.

 

 

 

Enduring Understandings:

 

·         Students will solve various types of addition and subtraction word problems and equations using strategies. 

·         Students will use place value to compare two numbers. 

·         Students will add two-digit and one-digit numbers with and without composing a group of ten.

·         Students will develop strategies for adding and subtraction whole numbers.

·         Students will understand that addition and subtraction are processes in which groups are joined and separated.

 

Essential Questions:

 

·         What happens when we join two quantities or take one from another?

·         How can we find the total when we join two quantities?

·         How can we find what is left when we take one quantity from another?

·         How can we find the difference when we compare one quantity to another?

·         How can we compare one quantity to another?

·         How can we represent problem situations?

·         How can we show that addition and subtraction are related?