7th Grade Math : Unit #4 - Operations with Rational Numbers : Lesson #16

Adding and Subtracting Signed Decimals - Line Up Those Points!

Objective: Students will be able to add and subtract positive and negative decimals.
Standards: 7.NS.A.1d 7.NS.A.3 MP1 MP3 MP6
Subject(s): Math
60 minutes
1 Launch - 5 minutes

Opener:  As students enter the room, they will immediately pick up and begin working on the opener.  Please see my instructional strategy clip for how openers work in my classroom (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

Learning Target:  After completion of the opener, I will address the day’s learning targets to the students.  In today’s lesson, the intended target is, “I can add and subtract positive and negative decimals.” 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). 

Adding and Subtracting Decimals Opener.docx
2 Explore - 55 minutes

Adding and Subtracting Signed Decimals Notes:  Adding and Subtracting Signed Decimals Explore Narrative

Table Practice:  To continue practice with both signed decimals and fractions, students will complete Adding and Subtracting Rational Numbers Puzzle at their tables. The sheet covers both positive and negative fractions and decimals, as students need time to work with both in order to build fluency. I will walk around and give assistance as necessary; most likely I will end up sitting with the lowest group to get them going! This sheet will become homework if it is not finished in class. It will continue to be very important for students to pay close attention to signs and integers rules, as precision will make all the difference in a right or wrong answer (mathematical practice 6).  

Instruction Reflection
Gradual Release

I try to steer away from the idea of me, we, two, you (gradual release) because I really feel it is the antithesis of common core.  I really feel like gradual release takes away the inquiry and natural thought processes of students.  That being said, gradual release was in full effect today :)  I had already taught this lesson to my advanced students, so I kind of knew what to expect in terms of misconceptions - the biggest misconception being that when you subtract you must take the number with the smaller absolute value from the number with the larger absolute value.  My advanced kids couldn't wrap their brain around that - at all.  So, going into this lesson - I modeled what really needs to happen to be successful with these problem types - specifically, I followed these steps: 1. Write the problem as an addition problem if it is not already; 2. Determine if you have the same signs or different signs, and then choose your operation accordingly; 3.  Look back at your signs and determine what the sign of your answer will be.  Since attention to detail is so crucial with these problems, I really felt like a concrete set of steps was important.  I found that as we moved past the instruction to the activity that students really did not require my help - which is good :)

3 Summarize - 2 minutes

Exit Problems:  As way to gauge understanding, I am going to have students solve two problems on the back of their opener, and turn it in on their way out of class.  One problem is a fraction, and the other is a decimal.  I just want to check for understanding as students will have a test in a couple days.