A-PLUS Writer

Josh Alessio

Problem solving using the “work backward” method.

Prepared for 6th grade math

Objectives of Lesson/Learner Objective

The students will be able to demonstrate their problem solving ability by working backward through word problems both in small groups and by themselves. The students will be able to show their work and complete the word problems using the work backward method as a group with no errors. The students will complete word problems individually using the backward method with 90% accuracy.

Anticipatory Set/Motivation/Snappy Launch

With your head full of brains and your shoes full of feet, you’re to smart to go down any not so good street. (“Oh the Places You’ll Go”, by Dr. Seuss)

Everybody needs to be able to solve real-life problems, and going forward doesn’t always take you down the right street. Today we are going to discuss a problem solving method that requires you to work backward.

Materials Needed/Preparation

I will provide the students with worksheets containing word problems.

Students need pencils, have some on-hand in case students don’t bring a pencil.

 

Procedure

1. I will go through two word problems using the “work backward” method.

2. After going through the first problem, I will define the work backward term.

3. Split into small groups and have the students come up with a word problem that requires using the work backward technique to solve. Solve the problem on a separate piece of paper, but keep the answer a secret. Trade problems with another group, and solve their problem. Compare answers.

4. Provide a worksheet with a couple word problems that will require using the work backward method of problem solving.

Vocabulary

1. Work Backward: When given the result of a sequence of operations, you can work backward to find the amount with which the sequence began. Discuss this definition in terms that are meaningful for all the students.

Examples

Example #1 (work backward)

The cat in the hat went to the flea market and spent $9.75. He bought some green eggs and ham, thing # one, and thing # two. The green eggs cost $1, the ham cost $1.25, and thing #1 cost $3. How much did thing #2 cost.

(9.75 – 1 – 1.25 – 3) = 4.50

Work Forward: Check your work by adding up all the components to get the result.

Example #2 (work backward)

On Monday there are 50 star bellied sneatches on the beach. That day, 8 star bellied sneatches had their stars removed. On Tuesday, 13 more star bellied sneatches had their stars removed. On Thursday, there were only 19 star bellied sneatches left on the beach. How many star bellied sneatches had their stars removed on Wednesday?

(50 – 8 – 13 - 19) = 10

Work Forward: Check your work by adding up all the components to get the result.

Check for Understanding

While the students work in groups, I will be an observer, walking around, making sure all the students are engaged and working with the smaller groups or individuals to gage and ensure understanding of the concept.

 

Clean Up Straighten up desks, hand in group projects, individual worksheets and any borrowed pencils.

 

Student Assessment

Students will be asked to solve word problems on a worksheet by themselves using the work backward method of problem solving. I will ask students to show their work, and give partial credit for work that shows they are using the work backward method of problem solving, along with giving credit for having the correct answer.

Lesson Evaluation – I presented my lesson to my mentor. Too much information was presented in the original lesson plan. I simplified the objective from solving with patterns, equations, and working backward to just solving problems with the work backward method. It was recommended that I include SMART goals in my objective, so I changed from no individual errors to expecting no group errors, and added a new goal for individuals to work at 90% accuracy. It was also suggested that I include a lead into other work or ideas. I added a section for checking your work by working forward through the word problem to check work. He really liked the idea of splitting into small groups. My mentor suggested giving partial credit for students who show their work.