Converting Capacity using Metric System

10 teachers like this lesson
Print Lesson


The students will be able to convert measurements of capacity within the Metric System.

Big Idea

Ready, aim, fire!


15 minutes

Today’s lesson focuses on converting capacity within the Metric System.  Students compete in a water balloon toss with a partner, and then determine the total amount of water used to fill the balloons.  Students present findings as to their total calculation of water used during the competition. 

Before starting today’s lesson I fill up balloons of various colors.  Each color gets a slightly different amount of water. For example, red balloons have approximately 50ml of water.  (These do not need to be precise.) I make at least twice the number of balloons as I have of students.

For the water balloon toss, students pair up and form two parallel lines; one partner on one line and the other partner on the other line.  The two lines start out very close to each other, about a foot apart.  The students take turns tossing the balloon back and forth when I give them the signal to toss.  After each toss, the students each take one step backwards from each other.  If a pair drops the balloon, they are out of the competition.  Play continues until the last pair is standing.  I play the game a few times or until the balloons run out. 

video of toss

Of course we make sure we pick up all the pieces of the balloons off of the ground. 


30 minutes

Once we return to the classroom I give students the task for the remainder of the lesson.  Before starting the task I ask students to get out their graphic organizer so that we can add our last piece of information to it for our unit of capacity. 

Today we used water balloons and I put different amounts of water in each balloon.  What type of measurement should we use when looking at how much something holds?  For the U.S. Customary system what units did we use?  What do you think we are going to use for the Metric System? 

Right, so now that we know we are going to be working with liters, do you think we can still use our mnemonic to help us convert liters?

I continue to probe students during our discussion to ensure they understand that converting liters is the same as converting meters and grams. 

I explain to students that now they will calculate the number of liters of water I had to use to fill the water balloons.  I provide students with the number of balloons used and the amount of water in each balloon color. 

12 red balloons with 45ml each

11 yellow balloons with 40ml each

13 green balloons with 50ml each

15 blue balloons with 47ml each

These are all the balloons we just broke outside.  I would like you to calculate the total number of liters of water I used when filling the balloons.  Might there be a few steps involved in solving this task? 

I would like you guys to work with your groups to determine the total number of liters used during the balloon toss.  At the end I will ask groups to come up and present their thinking of their calculation.  You should have all your calculations neatly recorded on a piece of paper for your presentation.  I would like you to create a model to accompany your calculations. 

The remainder of the time I allow the students to work with their groups while I circulate the room.  If groups are struggling I ask them to explain their thinking and ask probing questions to further their thoughts and steer them in the right direction. 


15 minutes

Groups present their findings on the task.   I listen for accuracy and academic vocabulary.  I also monitor to make sure each member of the group is participating in the presentation.  

Video student presentations