Perimeter - 3rd Grade

Lesson by Glen Jones (created 03/14/11 with the CalStateTEACH Lesson Plan Assistant)





The classroom has 25 students, with 15 girls and 10 boys.  The ELL ability of the students ranges from a 1 to 5, with the 5 students going to be removed soon given his high scores.  That can't be done without verifying with latest CST scores, but given the high number of ELL students and limited ELL resource concentrating resource on those that need it most is important.  There are a few challenging kids in class, with mainly trying to keep them focused and not disrupting other students, as well as some of the ELL students are writing several grade levels below 3rd, and a few reading at a low level as well.  This requires accomondations of the writing assignments and some of the reading assignments, as well as developing the vocabulary and connecting it to their personal backgrounds.

Subject Area(s)



Students will be able to find the perimeter of common shapes when all sides are not given.  The specific shapes I want them to be able to fill in the missing sides for are equilateral triangle, square, and rectangle, although other symmetrical shapes will be given to challenge the higher math students.


California Academic Content Standards

Mathematics, Grade 3
Measurement and Geometry | 1.0 Students choose and use appropriate units and measurement tools to quantify the properties of objects:
- Standard 1.3: Find the perimeter of a polygon with integer sides.


Students will be expected to complete the worksheet getting 75% of the questions correct.  The students will participate by asking and answering questions, using the SMART Board, and completing the assessment.  They will also share with each other common uses of perimeter on a farm so they may connect and to prepare them for an upcoming field trip.


I will collect a worksheet that has various problems involving perimeter.  Some of them just require the adding of integer sides, while some require them to use their knowledge of common shapes to fill in missing sides (for example, they get only one side of a square).  This assessment will allow me to see several things including:

1.       Which students are comfortable with the previous lesson when all sides are given.

2.      Which students understand the lesson taught today and filling in missing numbers

3.      Which students are excelling as one of the problems has symmetry, which has been taught, but I want to see if they can apply that knowledge.

4.      Which students understand the concept but are getting the answers wrong because of addition and multiplication errors.

Prerequisite Background Skills/Knowledge

The previous lesson was the introduction of perimeter when all integer sides were given, and with calculating perimeter of arrays.  The subsequent lesson will be area, so students will need to measure the inside versus the distance around.  It should logically follow and many good, relevant examples can be used from their lives, classroom, and playground.

Vocabulary/Language Skills

Perimeter has been previously introduced, but it will be revisited.

Classroom Management

Most of the work will be independent; however, the will be doing a pair/share to connect personallly to the concept.

Models of Instruction

This lesson will be a combonation of direct instruction with some cooperative learning.  This meets the needs by giving the students a chance to share with each other  how they personally connect to the concept of perimeter.


Perimeter assessment, math workbook, and math journal.

Technology Resources


Browser (i.e. Safari, Firefox), Document Camera

Technology Applied

I will use the document camera as well as the SMART Board to teach these concepts, and to help with doing progress-monitoring during the lesson by having the students demonstrate problems on the SMART Board.


Communicating Academic Learning Goals:

I will let them know that they will be learning about perimeter of common shapes, and relate it to things they are interested in.  For example, figuring out the perimeter of a swimming pool, or how it would apply to having a garden.  I will let them know how it figures into what else they will learn in this unit, namely area and volume.  The learning goals will be clearly stated on the board and what they are expected to learn.

Instructional Strategies:

Direction Instruction: The first would be to activate their prior knowledge of what we worked on the day before when we calculated perimeter with all sides given, and to make sure they still remember the definition of perimeter.

The next would be to relate it to something that will be relevant.  They are going on a field trip to AgVenture in 2 weeks and I want them to relate perimeter to a farm. 

Group Sharing: I will have them do a pair/share with a partner for 2 minutes then share out some of the findings.  The goal here is twofold.  One is to have them relate personally to something they will be involved in, and build to an upcoming social studies unit on agriculture.

Guided Instruction:  I will then take several of the common shapes and have the students tell me the characteristics of a rectangle, square, and equilateral triangle.  I will fill in numbers based on student responses.

Next will be guided practice, where I will demonstrate a problem and solution, and have one of the students demonstrate the answer on the SMART Board.

The last stage will be independent practice and the assessment.  Directions for the assessment will be clear as well as what a student is to work on once they have completed.

Student Activities:

Student will share with each other what they think uses for a perimeter would be on a farm.   These ideas tie into their upcoming field trip and social studies and science units we are doing.  Some of them will share out.

Student will participate in class discussion and some will be selected to work out a problem on the SMART Board.

Student will do guided work via the math workbook and I will check that work.

Students will do independent work and an assessment of the concept taught.

Student Grouping:

Students mainly work independently, although they are given an opportunity to pair/share and generate ideas about how perimeter would be used on a farm.

Materials /Technology and Other Resources:

Student will use their math book and math workbook as well as a special assessment I have modified for assessing this concept. 

In addition, I use the digital overhead and SMART Board to involve students in the learning process, as well as communicate information onto the SMART Board for discussion.  While I did not use them in this lesson I also like to use the Response Clickers often to get immediate feedback as to how the students are doing on the lesson.

Monitoring of Student Learning:

I monitor student learning by calling on different students as we are reviewing previous concepts and introducing new ones.  In addition, during pair/share I walk around and listen to their ideas.  I also monitor student learning by having students write answers on the SMART Board, which allows me to see how students are doing demonstrating their work and explaining their thinking to the whole class.  While students are writing on the SMART Board I can also walk around the room and check the students work, and make adjustments as necessary and reiterate a point.  I also make sure that during guided learning I closely monitor that they are paying attention.  In addition, I also circulate during independent work.


The lesson was effective given the pacing guide and the need to cover almost a new math concept a day.  The students understood how to calculate perimeter for sides that aren’t given, and had a good recollection of common shapes.  To improve the lesson I would get more students involved on the SMART Board, as it keeps them motivated to work the problems, and gives me a chance to go around the class monitoring the students, and providing assistance to the few that really need the concept reinforced.