Scaling Figures

Grade: Seventh

Time for Lesson: One class period

Objectives: The students should be able to understand the importance of scaling objects. They should be able to scale up and down an object when given a scale ratio and an object’s measurements. They should be able to measure an object accurately within one-sixteenth of an inch.

TEKS Objectives: 7.2, 7.3, 7.4, 7.5, 7.9, 7.13, 7.14, 7.15

Materials: Rulers (with cm), matchbox ™ cars with matching websites for their actual size, book: Cut down to size at High Noon by Scott Sundby, book: How big are they? by Flying Frog Publishing Barbie and Ken ™, Barbie and Ken ™ Worksheet, and calculators

Focus: The teacher will peek interest by showing an example of scaling up and an example of scaling down a figure. For scaling up the students will look at the book How big are they? by Flying Frog Publishing where they show many things already scaled up. The one we will be using is the yellow meadow ant; the small one is on page 10 where as the scaled up one is on pages 8-9. For scaling down the teacher will ask for a volunteer in the class. They will measure the height of the volunteer student’s height. Then the class will go into the hallway, a long one or outside, where the volunteer student will walk down it until they appear smaller. Allow the class to measure the new “height” of the student, which is the height they appear to be after they have walked away. After they have seen this the teacher will play the video about scaling from website: http://www.brainpop.com/math/problemsolving/scaledrawing/

Teacher Explanation/Modeling/Instruction: Read the book Cut down to size at High Noon by Scott Sundby to the class. As the teacher reads the book the following questions can be asked:

§ What time period does this book look like it will take place? (Before reading)

o During the days of the early west

§ How does Louie cut hair, scaled up or down? (p. 6)

o He scales down real objects

§ How does Louie scale the larger objects down? (p. 10)

o He draws the object on a sheet of paper then sees how he will scale those objects down by a specific ratio

§ What type of hairstyle do you think Buzzsaw will cut? (p. 18)

o Any answers will be fine since they are guessing

§ How does Buzzsaw cut hair, scaled up or down? (p. 24)

o He scales up real objects

§ Is there a way the two barbers can work together? (p. 27)

o There is no wrong answer to thing question either

Guided Practice: The students will be split into groups of 3-5. Before handing out supplies they should briefly describe how to use the master ruler to reinforce their understanding of the proper technique on how to measure. Each group will be given a Matchbox ™ vehicle, a master ruler, and the following directions:

Measure the length, width, and height of the vehicle you have been given in inches. Make sure it is to the closest one-sixteenth of an inch. Everyone in the group should have it written down.

The teacher should walk around and make sure the all the students are measuring properly. The next thing the teacher should do is line the students up and take them to the computer lab, or wherever they can have computer access. The following website http://www.conceptcarz.com/vehicle/default.aspx?carID=7436&l=A&optionID=2 (Acura) or http://www.conceptcarz.com/vehicle/z8344/default.aspx (Hummer) will be attached to the teacher’s website so the students can easily access it. This website will give them the measurements of the actual sized car that matches their little car they already measured. They are all to write these measurements on their sheets. The students can then look at the teacher’s website for the background information about scaling objects. The students will find the ration at which the matchbox ™ vehicles were scaled down from the actual vehicle size. They will figure out how many inches in the actual car equal ¼ inch for the matchbox car. This will vary depending on the car types and sizes. The two groups with the same cars will come together to discuss their findings and compare their results. We will all come together and discuss everyone’s findings as a class and answer any questions.

Independent Practice: The teacher will pass out the Barbie and Ken ™ dolls and a worksheet about their dimensions. The students are to scale Barbie or Ken ™ up to size for a real person. They will do this on their own and can use a calculator if they so desire. Once this is finished the students are to decide whether or not Barbie and/or Ken ™ could actually be a real person.

Closure: The teacher can ask any of the following HOTS questions to wrap up this activity:

Knowledge: In the book, Cut down to size at High Noon, how did the barbers scale up or down objects in order to be able to cut hair in that shape?

§ They drew a picture and labeled it. They then shrank each part down or increased each part by a specific ratio.

Comprehension: What does scaling an object mean?

§ It means to increase or decrease an object

Application: How do you scale up an object?

§ You measure the object and then increase each part by the same ratio

Analysis: What is the first thing you must do when want to scale down an object, such as an actual vehicle?

§ You must measure the objects dimensions for each part.

Synthesis: What profession would use scaling objects and why?

§ Landscape artists that make topiaries because they take animals and cut bushes to look like those animals

Evaluation: Summarize why scaling objects is important in the world around us?

§ Many answers will be acceptable

Extension: The teacher could give the students some butcher paper and have them draw Barbie ™ in the actual size with the proper measurements they discovered during their independent practice. The teacher can bring in many other objects that the students can scale up or down. The teacher can also have the students do some research about other objects in the world around them, anything that may interest them, and have the students scale them up or down and then have them draw a picture that is labeled.

Reteach: If the students do not understand the concept the first time it is taught, the teacher then must go back over the material. One way they could do this is to do a simpler example with just a 2-D shape and then work it sep-by-step in front of the class using the think aloud strategy. They can then do more examples with more complex shapes where the teacher will lessen their involvement with solving the examples.

Modification: If the school does not have a computer lab or a place where the students can gain access to a computer, the teacher can already have the measurements for the actual vehicle. A special needs student could have the notes already given to them so they can keep up with what is going on. They could also have their own car and ruler that they can measure. The teacher should also check in with the special needs students while they are doing the independent practice to make sure they understand what they should be doing.