7th Grade Math : Unit #7 - Geometric Figures : Lesson #1

Scale Drawings

Objective: Students will be able to apply the concept of proportional reasoning to solve scale drawing problems.
Standards: 7.G.A.1 MP1 MP2 MP3 MP4 MP5
Subject(s): Math
60 minutes
1 Launch - 10 minutes

As students enter the room, they will immediately pick up and begin working on the Opener.

Instructional Strategy - Process for openers.  This method of working and going over the opener lends itself to allow students to construct viable arguments and critique the reasoning of others, which is mathematical practice 3

After completion of the opener, I will address the day’s Learning Targets to the students.  For today’s lesson, the intended target is “I can use proportional reasoning to solve scale drawing problems.” Students will jot the learning target down in their agendas (our version of a student planner, there is a place to write the learning target for every day). 

2 Explore - 45 minutes

Scale Drawings NotesExplore Video In this lesson, students are using their knowledge of ratios and proportional reasoning to find unit rate, and thus solve for unknowns in scale problems.  Through the openers, I have tried to spiral the concept of unit rate throughout the entire course, thus applying it in this lesson does not come as a major road bump for students.  The largest issue I have seen students have with this concept is the mixing of the units - they do not want to make a rate out of 1 inch equal to 50 miles - because in reality one inch is not equal to 50 miles.  However, I try to remind students that they are working in the context of a problem, they are not working with real conversions.  Having maps and other scale drawings available for kids to reference is very helpful!  This lesson is also a good use of mathematical practices 3, 4, and 5 - as students are working together and giving one another feedback on their work (3), and this lesson lends itself to modeling real world situations (4).  Additionally, students use tools (5) such as rulers to determine scale values.

White Board Practice: The use of white boards in small groups allows me to see which tables are struggling, and position myself to give them immediate feedback and help.  I like to correct problems as they are happening as opposed to finding out there is an issue after they have left my class.  Forcing the kids to rotate the board gives every child an opportunity to write and solve problems, and gives me, the teacher, the opportunity to see if they get it!

Instruction Reflection
Connection to Prior Knowledge

This was the first year I eliminated proportions from my instruction.  After reading a lot about the common core, and having vertical conversations with teachers in my district - proportions are really more of a hindrence to student learning.  Sure, they offer a quick, easy way to set up a problem - but they lack longevity.  This year I have focused my teaching on proportional relationships to build on unit rate - and teaching this lesson using the proportional equation I think will better withstand the test of time.  Students caught on to the concept, and they were able to easily relate it back to what we did at the beginning of the year.

3 Summary - 5 minutes

Instructional Strategy - Table DiscussionTo summarize this lesson, I am going to ask that students have a table discussion on a question that requires students to take it a step further and find the dimensions of a figure, not just the measurement of one side.  Though this concept is not any harder, for some reason the term “dimensions” throws kids off.  Thus, this summary activity will allow students the opportunity to see and work with the term in a group setting.  Teacher observations during this discussion allow me to hear who is getting it and who is not.  Though this is a more challenging problem, students who have a good grasp on the concept will be able offer sound reasoning to their table regarding how to start this problem.