Primary Type: Lesson Plan
Status: Published
This is a resource from CPALMS (www.cpalms.org) where all educators go for bright ideas!
Resource ID#: 49485
The Secret Agent Symmetry Man!
Do you know your ABC's? Well, you won't be learning them here, but you will find out which upper case letters contain one, two, or no lines of
symmetry. Your students will know that a line of symmetry is a line across a figure that the figure can be folded along the line into matching parts.
Students will be focused and engaged during the Promethean Planet flip chart lesson that explores mirror symmetry and more. Students will walk
away from this lesson feeling confident in their abilities to see symmetry in two dimensional figures and in objects in their world!
Subject(s): Mathematics
Grade Level(s): 4
Intended Audience: Educators
Suggested Technology: Computer for Presenter,
Internet Connection, Interactive Whiteboard
Instructional Time: 2 Hour(s)
Freely Available: Yes
Keywords: symmetry, two-dimensional figure, line-symmetric figure
Resource Collection: CPALMS Lesson Plan Development Initiative
LESSON CONTENT
Lesson Plan Template: General Lesson Plan
Learning Objectives: What should students know and be able to do as a result of this lesson?
Students will know that a line of symmetry (also called mirror symmetry) as being a line across the figure such that the figure can be folded along the line into
matching parts.
Students will know how to identify line-symmetric figures.
Students will draw lines of symmetry.
Prior Knowledge: What prior knowledge should students have for this lesson?
MAFS.3.G.2 States that third graders partition shapes into parts with equal areas.
This knowledge will help the students see in fourth grade that a line of symmetry is like separating the shape into equal halves or equal areas.
Guiding Questions: What are the guiding questions for this lesson?
1. How do you know that a figure has symmetry? (answer) When the line is drawn down the middle of the object, the figure is identical on either side of the
line.
2. How can you be sure you've found all the lines of symmetry for a figure? (answer) Draw a real or imaginary line cutting the figure into halves. The halves
need to look exactly the same on both sides.
3. How are symmetrical figures created? (answer) A student can fold the paper in half, both halves should look identical.
4. How did you know which letters had symmetry? (answer) The letters where identical when folded in half or when a line was drawn down the middle of the
letter.
5. How did you know you found all the lines of symmetry for a letter? (answer) Students can use a ruler to draw a straight line from the estimated midpoint
through the shape. Students can fold the shape if possible to see if both sides match. Students can check all the angles of a shape to look for all possible lines of
symmetry. Students can hold a small mirror perpendicular to a possible line of symmetry. If the shape in the mirror matches the shape on your paper, you have
found a line of symmetry.
Teaching Phase: How will the teacher present the concept or skill to students?
1. Students will explore mirror symmetry through a variety of scaffolded activities. This is a hands on activity that can be used with the interactive white board or
page 1 of 3 projected on a screen. Students will enthusiastically come forward to partake in this activity. Students will understand that a line of symmetry as a line across a two
dimensional figure. They will see each figure as having matching parts.
2. Go to the website Promethean Planet. http://www.prometheanplanet.com/en-us/
The Promethean Planet website does sell products but are not necessary to buy to use the flip charts. A free account and download of ActivInspire software is
required for download and viewing. Files (.flp) can be opened "PowerPoint" style with interaction on the computer as opposed to on an interactive whiteboard.
Type in "mirrors symmetry" in the search box. The first flip chart will be the one that the teacher uses.
Slide one will have a triangle on the right side of the line. The students must choose the correct triangle to make the figure symmetrical.
Slide three will be a bit more difficult. The students will need to combine two shapes to make the figure symmetrical.
Slide 6 will need a lot of teacher assistance. There are many shapes to add to make the figure symmetrical. It will be a fun challenge for the class to do
together. This is also the example students will use before their Guided Practice.
Guided Practice: What activities or exercises will the students complete with teacher guidance?
1. Students need a plain sheet of paper with a straight line through the middle. Using about six to eight pattern blocks, students make a design completely on one side
of the line that touches the line in some way. The task is to make the mirror image of their design on the other side of the line. When finished, they use a mirror to
check their work. They place the mirror on the line and look into it from the side of the original design. With the mirror in place they should see exactly the same
image as they see when they lift the mirror. You can also challenge them to make designs with more than one line of symmetry. (Have the line pointing towards the
student. This will make it easier for them to see it as it develops.) The teacher will walk about helping the students complete this activity. *this activity will work
well with the Promethean Planet activity
2. Students will need copies of the 26 letters of the alphabet (click to open). Students will find the letters that have one line of symmetry. (A,B,C,D,E,K,M,T,U,V,W,Y)
3. Students will then find the letters that have two lines of symmetry. (H,I,O,X)
4. Students will then realize the rest of the letters have no lines of symmetry. (F,G,J,L,N,P,Q,R,S,Z)
Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the
lesson?
Students will write one half of a letter on a piece of paper. They will partner up with another student who will try to guess what the letter is.
Have the students practice writing secret letter to themselves first . As students progress, they can be secret agents and write messages to their partner.
The letters above would be in order M,A,T,H. If the students would have chosen these letters to be their secret code, the word would be of course MATH.
Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?
http://www.amazon.com/Seeing-Symmetry-Loreen-Leedy/dp/0823427625/ref=sr_1_2?s=books&ie=UTF8&qid=1374675488&sr=1-2&keywords=symmetry
1. The book by Loreen Leedy, "Seeing Symmetry" can be purchased used on Amazon for $2.65.
2. Show the students the different pictures and discuss the symmetry that each picture shows.
3. Talk about why each figure is symmetrical.
4. Ask the students what would make each picture not be symmetrical.
Summative Assessment
1. The students will look around the classroom and write down three objects that have at least one line of symmetry. They will then explain to the class why their
object is symmetrical.
2. Students will write in their own words what symmetry is.
3. Students will create a new and unusual symmetrical design using pattern blocks. The teacher will circulate around the room to make sure each student's design is
symmetrical.
Formative Assessment
Teachers can ask the following questions before, during, and after the lesson to assess student understanding and plan accordingly.
1. How do you know that a figure has symmetry? (answer) When the line is drawn down the middle of the object, the figure is identical on either side of the
line.
2. How can you determine the lines of symmetry in a figure? (answer) Students can use a ruler to draw a straight line from the estimated midpoint through the
shape. Students can fold the shape if possible to see if both sides match. Students can check all the angles of a shape to look for all possible lines of symmetry.
Students can hold a small mirror perpendicular to a possible line of symmetry. If the shape in the mirror matches the shape on your paper, you have found a
correct line of symmetry.
3. How did you know you found all the lines of symmetry for a letter? (answer) Draw a real or imaginary line cutting the figure into halves. The halves need
to look exactly the same on both sides.
Feedback to Students
Students will get feedback during the Promethean Planet flip chart lesson about mirror symmetry. This will help them to see that symmetry is a line across a two
dimensional figure.
Students will get feedback during the pattern block mirror activity. They will use this information to help them to see symmetry in letters.
Students will get feedback during the alphabet symmetry activity. This feedback will help them to become secret agents as they write half letters for their partners
to complete.
page 2 of 3 ACCOMMODATIONS & RECOMMENDATIONS
Accommodations:
Give students paper pattern blocks to fold and have them draw lines of symmetry directly on the paper blocks. Ask students to draw the second half of a given
symmetrical figure with only one line of symmetry.
Ask students to draw the second half of a given symmetrical figure with two lines of symmetry.
As students trace a pattern block on one side of the line of symmetry, have them immediately flip the block over the line of symmetry and trace it right then. This
will help them see the mirror image immediately.
Give students multiple copies of the letters to cut along the lines of symmetry to write their code. Their partner can give them the pieces that we cut off when the
code was made to match up and complete the letter as they break the codes.
Extensions:
Students may use a draw tool in word processing software or a paint program in order to draw quadrilaterals with a specified number of lines of symmetry.
Students may work in pairs and then report to the whole class.
Give students the alphabet (upper case letters only) printed in other styles or fonts to complete in another ABC symmetry chart.
Give students multiple copies of the letters to cut along the lines of symmetry to write their code. Their partner can give them the pieces that were cut off when the
code was made to match up and complete the letter as they break the codes.
Share the book, Seeing Symmetry by Loreen Leedy
http://www.amazon.com/Seeing-Symmetry-Loreen-Leedy/dp/0823427625/ref=sr_1_1?ie=UTF8&qid=1373471902&sr=8-1&keywords=seeing+symmetry
Share the book, What Is Symmetry in Nature? (Looking at Nature) by Bobbie Kalman
http://www.amazon.com/What-Is-Symmetry-Nature-Looking/dp/0778733475/ref=pd_bxgy_b_img_y
Suggested Technology: Computer for Presenter, Internet Connection, Interactive Whiteboard
Special Materials Needed:
Copies of the upper case alphabet (attached)
Pattern blocks
Paper pattern blocks
Small mirrors
Further Recommendations:
Previewing the Promethean Planet flipchart which will help in your presenting the material.
Additional Information/Instructions
By Author/Submitter
This resource is likely to support student engagement in the following the Mathematical Practice: MAFS.K12.MP.7.1 Look for and make use of structure.
SOURCE AND ACCESS INFORMATION
Contributed by: Ron Silianoff
Name of Author/Source: Ron Silianoff
District/Organization of Contributor(s): Brevard
Is this Resource freely Available? Yes
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
MAFS.4.G.1.3:
Description
Recognize a line of symmetry for a two-dimensional figure as a line across the figure such that the figure can be folded
along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.
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