Date conversion 02.12.2016 Size 19.8 Kb.

The learning centers presented in this section are designed to have students engaging in tasks that relate to addition and subtraction of two-digit numbers with and without regrouping. These tasks can be used for assessment purposes. For most tasks students should be provided with concrete materials such as base ten blocks, number lines, and hundreds charts. These activities are based on switching representations as indicated.
B9 model and perform the addition of two 2-digit numbers, with and without regrouping

B10 model and perform the subtraction of two 2-digit numbers, with and without regrouping
Students choose a card from the pile and complete the question using the base ten materials. They then sketch a picture of what they did with the concrete materials and write the solution. There are both addition and subtraction cards so students should choose one of each to complete. Some of the cards require regrouping and others do not so students who are struggling with regrouping can work on some of the questions without regrouping before moving to those with regrouping. This activity could be varied by having the students find the solution by using a number line or a hundreds chart. Students might also be asked to show the solution using each of these representations, or two of the three.
Representations: Symbolic to concrete and pictorial
B9 model and perform the addition of two 2-digit numbers, with and without regrouping

In this activity students choose two cards from the pile of base ten models and place them on the mat, then perform the addition indicated. They should build it using base ten materials and then record a picture to show their solution.

Representations: Pictorial to concrete, pictorial, and symbolic
B9 model and perform the addition of two 2-digit numbers, with and without regrouping

B10 model and perform the subtraction of two 2-digit numbers, with and without regrouping

B3 demonstrate an understanding that addition can be used to solve subtraction problems
There are nine different word problems presented for students. Students are to select one of the word problems and complete it, showing their work on the recording sheet provided. Each of the problems presents a context in which addition or subtraction is required. Some will require regrouping and others will not. Students can be encouraged to use base ten materials, hundreds charts or number lines to solve these problems. The problems vary in difficulty both based on the numbers involved in the problems and by the structure of addition or subtraction problem presented. See below. Other structures could be incorporated into this activity and more problems of each type could be added.

 1 Join: Result Unknown 4 Separate: Result Unknown 7 Part-Part-Whole: Whole Unknown 2 Join: Change Unknown 5 Separate: Initial Unknown 8 Part-Part-Whole: Part Unknown 3 Join: Initial Unknown 6 Part-Part-Whole: Whole Unknown 9 Compare: Difference Unknown

Representations: Contextual to concrete, pictorial, and symbolic

B9 model and perform the addition of two 2-digit numbers, with and without regrouping

B4 create word problems involving addition and subtraction
This activity has four variations, three of which involve regrouping and one which does not. Students should choose one of the four activities and complete it as directed. Students will be expected to complete the picture, write a number sentence and create a story problem to match the picture and number sentence.
Representations: Concrete and pictorial to symbolic and contextual
Write a story problem

B9 model and perform the addition of two 2-digit numbers, with and without regrouping

B4 create word problems involving addition and subtraction

Students are asked to create a story problem in which they would need to add two 2-digit numbers that are both greater than 20.

Representations: Contextual
What’s the difference?
B10 model and perform the subtraction of two 2-digit numbers, with and without regrouping
Students play a game similar to the adding game, except here they find the difference between the two numbers using the hundreds chart. They should identify both numbers in the hundreds chart and then show how to count backwards using jumps of tens and ones. They record a subtraction sentence to show their result.
Representations: Pictorial and Symbolic.
Roll It!
B9 model and perform the addition of two 2-digit numbers, with and without regrouping

B10 model and perform the subtraction of two 2-digit numbers, with and without regrouping
In this activity students roll four dice and record the digits. They then use these four digits to place the numbers in the boxes to make the greatest sum and the least sum. They then use the same digits to create the greatest difference and the least difference. This task can be adapted by allowing students to do only the addition or only the subtraction questions or by allowing students to do two of the four of their choice. Eight or Ten-sided dice may also be used to change the complexity of the task.
Representations: Symbolic.
Subtraction Number Lines
B10 model and perform the subtraction of two 2-digit numbers, with and without regrouping

In this activity, students chose two cards from the box (from 3 to 30) and record the numbers on their sheet. They then locate the two numbers on the number line and determine the difference between the two numbers. They record this in a subtraction sentence.

Representations: Pictorial and Symbolic.

Name: ___________________________

 Write a story problem Addition and Subtraction Problems The Adding Game Tell me an Addition Story Choose any 6 of the activities Addition and Subtraction Cards What’s the difference? Roll It! Subtraction Number Lines