The Video Game Model of Adding

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SWBAT create and verbally explain and demonstrate, with models and equations, multiple ways to add on from a given number to 2000 using repeated addition of 50 and 100 and multiplication of 50 and 100.

Big Idea

Video games often dole out points in groups of 25, 50 and 100 because they are easy numbers to multiply. Practice with patterns of 5 and 10 apply directly to understanding patterns with 50 and 100.


3 minutes

This lesson is based on the reward structure in a popular video game called Plants versus Zombies.  While almost all of my 3rd graders play it, I have not linked to information about the game because it's rated for 10 years old and above.

Your students most likely will recognize what this lesson is patterned after, but I do not want to suggest you use an inappropriate resource in your lesson. If you are unfamiliar with this game, and would like to see the model I've providing a link to a subcomponent  of the original version of the game.  As this is not recommended for the age group of our students, I am not endorsing watching this video clip in class.   

The intention of this lesson is twofold.  First, in my classroom there is often a correlation between reluctant students and video game use.  Therefore, I have found the use of video games, even very briefly to be an effective tool to get these children "on board".   So I am using this as an engagement tool.

Secondly, whether students are gamers or not, the format of online games such as this provide a useful, familiar structure through which students can gain further hands-on and written experience with repeated addition and multiplication patterns.

As the lesson opener, I simply ask the students who is familiar with the game and then ask them to “30 second think” (silent) about what they know about how points are awarded in the game.  If they are unfamiliar with the game, I ask them to think about video games with which they are familiar and apply the same question.  Occasionally, I will have a student who does not play video games.  I ask them to think about how they would award points if they were running a simple carnival game such as a bean bag toss. 

After the “30 second think” I have them share their thoughts with an immediate neighbor for 1-2 minutes.

Then I explain that we are going to use an imaginary video game modeled after a simple, popular game to help us practice repeated addition and multiplication.  (The repeated addition should quickly be replaced by the multiplication, but I leave it in as a scaffold for any students who need the reassurance of the familiar and/or extra support). 

Then I show the PowerPoint which immediately begins to address this task.   It narrates itself.

Guided Practice

22 minutes

Go through these simulated video game examples of adding on 50 and 100.  Encourage the students to work through the examples with you and attempt them on their own when they are ready.

The idea of representing an unknown factor or addend with n instead of a ? is presented in the lesson.  If your students are not yet familiar with this concept, explain to them that n or any letter can be used to represent an unknown quantity, and that this is the way that unknown variables are represented in higher level math.  

I prefer to do this part of the lesson on whiteboards or scrap paper to discourage the students from becoming too absorbed in formatting the problems correctly.  The emphasis here is on the thinking.

Independent Practice

33 minutes

Students work independently or in partnerships to solve problems similar to those in the guided practice.

Provide the 50 star and 100 star cards so that they can create models to help solve the equations (MP4, MP7).  This is the type of activity in which it can be very helpful to take anecdotal notes.  The box on my anecdotal notes that says "score" can apply to system you use - it might be a letter grade you would give that particular problem, it could be a rubric grade, it could be a star, check plus, check, check minus...  anything that helps you retain a picture of what the child said and did that indicated their level of understanding of the process of adding on and multiplying with the amounts of 100 and 50). 


4 minutes

To close, ask the students to share a strategy they use for adding on 50 or 100 or for using a combination equation that includes multiplication.  Students can then report out on their own ideas or those of a partner, time permitting. The rigor of the activity is derived from the contextualizing of their learning, so it is critical that you do not leave out this closing step. 

Support students in explaining their thinking by inviting them to use concrete representations (e.g., drawings, manipulatives, number line). Third grade students are developing language and communication skills, so the goal is to create successful situations. Using concrete materials provides students with a starting point, because they can use them to describe and/or recreate.