Missing or Extra Information

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SWBAT identify the essential information that is needed to solve real-world problems.

Big Idea

Sometimes word problems contain information that is not needed in order to solve the problem.


5 minutes

I let the students know that today we will do a task.  I remind the students of the structure and routine of a task.  First, the students have private work time to think about and plan how to solve the task.  Next, the students work in groups to explore the concept of the lesson.  Finally, the students share/analyze/and discuss the task as a whole class.  Each student has a copy of the task at their desk and a place value chart.  We have already learned how to use place value to add.

In today's lesson, the students use their understanding of finding missing numbers to solve this task without direct instruction.  (The students have had practice with finding the value of a variable, as well as finding missing numbers in equations.)  In this lesson, the students utilize their knowledge of adding decimals to find the missing or extra information.  They will be guided to the answer through questioning by me as they work in their groups.  They have to find the solution by determining if they have all the information needed or if there is extra information given in the problem. (4.OA.A3).


5 minutes

After handing out the days task, I give the students about 5 minutes of independent time to read and plan to solve this problem (MP1).   After the 5 minutes of independent planning, the lesson goes to the next phase of group exploration.

 How Much Did She Spend:

hot dogs


potato chips




















Tina went to the football game with her sister, Sarah.  During half time, Tina visited the concession stand to purchase food for herself and her sister.  Tina purchased 1 hot dog, 1 hamburger, 2 drinks, and 2 bags of potato chips.  How much money did Tina spend?  _________


What information from the menu was extra information?  

Was there any information missing in order to solve this problem?  

Group Exploration/Discovery

20 minutes

During the group exploration/discovery phase, the students work in pairs.  Each group has a copy of the task.  The students share the same copy of the task because I want to make sure they work together to discuss the task. The students are required to find out how much money Tina spent at the concession stand.  The students reason abstractly and quantitatively by decontextualizing the information from the task and representing it symbolically (MP2).  During this phase, the students do not receive direct instruction.  In this lesson, they apply skills previously learned.   The students are guided to the conceptual understanding through questioning by their classmates, as well as by me.  The students communicate with each other and agree upon the possible ways to arrange the chairs.  This takes discussion, critiquing, and justifying of answers by both students.  As the groups discuss this task, they must be precise in their communication within their groups using the appropriate math terminology for this skill.  As I walk around, I am listening for the students to use "talk" that will lead to the answer.    

During the phase, I monitor and assess the students' progression of understanding through questioning.  Possible questions to help lead to the solution are as follows:

1.  What is the task asking you to find?  

2.  What information is needed to solve this problem?

3.  Is there any information in this problem that is not needed?

4.  What will you do with the extra information?

Any groups that finish the assignment early, can go to the computer to practice the skill at the following site until we are ready for the whole group sharing. 


15 minutes

During this phase of the lesson, student solution paths are shared.  While the students were working in groups and I was walking around questioning, I identified solution paths to be shared as a whole class for this phase.  

I call groups to the front to share their solutions.  This is a teaching opportunity for the few students who may still not know how to identify missing or extra informaiton.  This part of the lesson is lead by the teacher through asking assessing questions.  The students may also have questions that they would like to ask.  I use a document camera to display the student work (Student Work - Missing or Extra Information) on the Smart board for all students to see.

During this phase, I like to organize the sharing of the solution paths in a strategic manner.   I begin with a group that did an excellent job of identifying all of the information needed to solve this problem.  From there, we discuss any information that was not needed for this problem.  I bring out the point that it is very important to know extra information when we see it.  If we are not able to determine if the information is extra, then we may try to calculate it into the answer. Last, we hear the solution to the task. 

I feel that this is a well rounded lesson on identifying missing or extra information because the students are responsible for their own learning.  They have been given the tools and resources necessary to accomplish solving the task.




10 minutes

After the share/discuss/analyze phase of the lesson, I close the lesson out by having the students do an exit ticket.  This will enable me to see if the students can identify missing or extra information when solving word problems.    

The students will receive an Exit Ticket Missing or Extra Information to complete their answers.  I will collect these exit tickets to evaluate the students' understanding.  Those students who need remediation will work with me in small group the next day.

In this Video - Missing or Extra Information, I explain why an exit ticket is very important.