Hamilton-Wentworth DSB Lesson Study #1

Desk Arrangements

by Christine Nichol-Skirrow, OCT (facilitator), Laurie Leavens, OCT, Julie E. Burgess, OCT

The Problem-Solving Context

Lesson Focus

Skip counting
Repeated addition
Unitizing
Drawings to represent repeated addition

Curriculum Expectations

Overall: Solve problems involving the addition and subtraction of single- and multi-digit whole numbers using a variety of strategies, and demonstrate an understanding of multiplication and division.

Specific: Relate the multiplication of one-digit numbers and division by one-digit divisors to real-life situations using a variety of tools and strategies (place object in equal groups, use arrays, write repeated addition or subtraction sentences).

Problem Description

Arrange 24 square tiles into various groupings.
The context of a classroom and desks is used.

Actual Problem

Mrs. Nichol’s best friend, who is also a teacher, got a new job over the March break. After Easter weekend she will begin teaching a Grade 3 class of 24 students. She needs some ideas for setting up the 24 desks in her classroom. Design a variety of arrangements for the desks in her room. When creating your designs, remember to group the desks together. Use pictures, numbers and words to explain your designs.

Materials

• Problem copied onto ledger paper
• Markers
• Coloured tiles
• Large grid paper (same size as coloured tiles)
• 10x10-inch overhead grid
• Overhead coloured squares

The Problem

Getting Started

As a whole class, discuss the design of the classroom. To represent the actual classroom design, use a 10x10-inch overhead as a floor plan and overhead squares as students’ desks. Write key math vocabulary like “groups of” and “row” on the board, as students utilize these terms to describe the classroom layout. Using square tiles and grid paper, re-create the classroom design, together with students, on the carpet area.

Working on It

Using random groups or elbow partners, students solve the problem creating various designs (each design should be put on a separate sheet of paper for use in math congress). Part-way through the lesson, stop student interaction and state that, for each design, the students must record how they determined that they used 24 desks.

Anticipated Student Responses

Repeated Addition:

Various groupings and addition.

The students may be able to unitize different groups and add the units together to find the number of desks (24).
Some students may begin using the multiplication symbol while describing the groups of desks.

Reflecting and Connecting

Gallery walk: After all groups have created two or more different designs, have students randomly post designs in the hallway. Have students walk around viewing the various designs, looking for those exactly the same as theirs. Re-post like designs on the board in the classroom, highlighting the use of repeated array addition (6 + 6 + 6 = 18) and multiplication (6 x 3 = 18) to describe the same design.