ALEX Lesson Plan


How Big Should it Be?

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  This lesson provided by:  
Author:Tim McKenzie
  General Lesson Information  
Lesson Plan ID: 33091


How Big Should it Be?


This lesson will allow students to become familiar with the concept of equivalent ratios and similar objects. Through an open investigation, students will develop methods to find equivalent ratios. This is a lesson to be used as part of a unit with Painter Problems and How Far Can You Leap found in ALEX.

This is a College- and Career-Ready Standards showcase lesson plan.

 Associated Standards and Objectives 
Content Standard(s):
MA2015 (6)
1. Understand the concept of a ratio, and use ratio language to describe a ratio relationship between two quantities. [6-RP1]
Examples: "The ratio of wings to beaks in the bird house at the zoo was 2:1 because for every 2 wings there was 1 beak." "For every vote candidate A received, candidate C received nearly three votes."
MA2015 (6)
3. Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations. [6-RP3]
a. Make tables of equivalent ratios relating quantities with whole-number measurements, find missing values in the tables, and plot the pairs of values on the coordinate plane. Use tables to compare ratios. [6-RP3a]
b. Solve unit rate problems including those involving unit pricing and constant speed. [6-RP3b]
Example: If it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours' At what rate were lawns being mowed'
c. Find a percent of a quantity as a rate per 100 (e.g., 30% of a quantity means 30/100 times the quantity); solve problems involving finding the whole, given a part and the percent. [6-RP3c]
d. Use ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities. [6-RP3d]
MA2015 (7)
2. Recognize and represent proportional relationships between quantities. [7-RP2]
a. Decide whether two quantities are in a proportional relationship, e.g., by testing for equivalent ratios in a table or graphing on a coordinate plane and observing whether the graph is a straight line through the origin. [7-RP2a]
b. Identify the constant of proportionality (unit rate) in tables, graphs, equations, diagrams, and verbal descriptions of proportional relationships. [7-RP2b]
c. Represent proportional relationships by equations. [7-RP2c]
Example: If total cost t is proportional to the number n of items purchased at a constant price p, the relationship between the total cost and the number of items can be expressed as t = pn.
d. Explain what a point (x, y) on the graph of a proportional relationship means in terms of the situation, with special attention to the points (0, 0) and (1, r) where r is the unit rate. [7-RP2d]
MA2015 (7)
11. Solve problems involving scale drawings of geometric figures, including computing actual lengths and areas from a scale drawing and reproducing a scale drawing at a different scale. [7-G1]

Local/National Standards:

Math Practice Standards:

  • Make sense of problems and persevere in solving them.
  • Reason abstractly and quantitatively.
  • Construct viable arguments and critique the reasoning of others.
  • Model with mathematics.
  • Use appropriate tools strategically.
  • Attend to precision.
  • Look for and make use of structure.
  • Look for and express regularity in repeated reasoning.

Primary Learning Objective(s):

I CAN identify and develop ratios in real world situations.

I CAN identify equivalent ratios.

I CAN compare ratios in real world situations.

Additional Learning Objective(s):

 Preparation Information 

Total Duration:

61 to 90 Minutes

Materials and Resources:

  • How Big Should It Be Activity Guide (found in attachments)
  • Investigative Activity Rubric (found in attachments)
  • Ratio 2 Exit Slip (found in attachments)
  • Chart paper
  • Yard stick
  • Math Toolbox which includes the following: pencil, paper, graph paper, markers, scissors, glue, calculator, and sticky notes

Technology Resources Needed:

Interactive Whiteboard (Optional) with required software, Document camera, projector, laptop or computer capable of showing videos (TV and DVD player can be used if the DVD is available). 


  • The teacher must make the appropriate number of copies of the How Big Should It Be activity guide (found in attachments). Copies should be made so that students can work collaboratively. 
  • The teacher must make the appropriate number of copies of the Ratio 2 Exit Slip (found in attachments). Each student should have one.
  • Teacher must prepare the appropriate number of Math Toolboxes.
  • Teacher must download the video at the link below.  Zoolander Center for Ants (If YouTube is not available through your school system, you may download the video using
  • The students must have knowledge of ratios.


  1. Teacher will show the students the video clip of Zoolander (video shows an unintelligent supermodel angered at the reveal of a model of a building, he claims the building is for ants and has to be at least three times as big). The teacher will ask the students, "Why did Zoolander get so upset at Mugato?" Ideal response, "He thought the model of the building was the actual building." The teacher will ask, "What do you think about his statement 'The building has to be at least three times that big'?" Ideal response, "three times as big would still not be big enough for anyone to fit in." 
  2. The teacher will introduce the idea of a scale factor as "a ratio used to enlarge or shrink any shape or object." 
  3. The teacher will present the How Big Should It Be activity (found in attachments). The teacher may have to demonstrate how to measure.
  4. Students will begin the investigative activity. They will be producing a poster with a shape 5 times the original size and 10 times the original size. The teacher will act as a facilitator and coach throughout the investigation. The teacher should address misconceptions and drive inquiry related to ratios. 
  5. Once adequate time (30-45 minutes) is given, the students will share their findings on the document camera. (If a document camera is not available, students may present their work in the front of the class, this is where the students would need chart paper). As the students are sharing, the teacher is acting as the facilitator and coach asking questions that drive ratio understanding. "How did you know to multiply by _____?" "How did you know to do _______?" "Did someone do this differently?" 
  6. Students will complete the Ratio 2 Exit Slip.

**Some files will display in a new window. Others will prompt you to download.

Assessment Strategies

Formal formative assessment: Ratio 2 Exit Slip

Formal Assessment: Using the Investigative Activity Rubric (found in attachments) teacher will evaluate students' work.

Informal Formative Assessment: As the students are working, the teacher will act as the facilitator and coach. Teacher will ask questions to evaluate students (i.e. How do you know ______? What did you do to get that?) Teacher may pull small groups during investigation on a needs basis.


The investigation has an included extension on the How Big Should It Be Activity Sheet (found in attachment)

Because this is part of a unit, teacher may develop small groups based on the Ratio 2 Exit Slip or informal questioning as part of the investigative activity.



Struggling students should be grouped with a peer tutor and teacher should pay close attention to those groups to assure complete understanding.

Each area below is a direct link to general teaching strategies/classroom accommodations for students with identified learning and/or behavior problems such as: reading or math performance below grade level; test or classroom assignments/quizzes at a failing level; failure to complete assignments independently; difficulty with short-term memory, abstract concepts, staying on task, or following directions; poor peer interaction or temper tantrums, and other learning or behavior problems.

Presentation of Material Environment
Time Demands Materials
Attention Using Groups and Peers
Assisting the Reluctant Starter Dealing with Inappropriate Behavior
Be sure to check the student's IEP for specific accommodations.