Volume

Volume of solid figures is one of our last objectives to cover before our state testing so we typically have very little time to teach it in. I try to pack as much instruction as possible into one class period. I've found that if I provide concrete, hands-on experiences and the opportunities for students to construct meaning on their own, they retain the information very well. Another way that I cope with the lack of time is by including volume questions throughout the year on our mixed-topic review sheets. This gives them a lot of exposure with the concept before I teach it.

In Texas our current standard (4.11C) states that students should be able to use concrete models to measure volume. This connects to 5th grade Common Core standard (5.MD.C.4) that states that students should be able to measure volume by counting unit cubes. I like to extend on our state standard by having students discover the formula for volume. This corresponds to the Common Core standard 5.MD.C.5.B - students should be able to apply the formula V=l x w x h to find the volume of rectangular prisms.

Mini-Lesson:

I started off our lesson by reviewing the formulas for area and perimeter. This activated their prior knowledge about formulas and got them thinking about measurement. I passed out unifix cubes* to each table and displayed a picture of a rectangular prism for students to build. This also gave us a great chance to review the vocabulary rectangular prism. Once they had built the prism we worked together to fill out the dimensions (length, width, height) and volume on a recording sheet. Our working definition of volume was "how many cubes did we use to build this figure?"

*Whenever we use a manipulative in math, I typically set a timer for 5 minutes and let the kids play. They know that if they play with the manipulatives after the timer goes off there will be a consequence. 

Partner Activity:

I had the kids work with their "face partner" (the person sitting across from them). Each pair got a set of task cards that had pictures of rectangular prisms. Their job was to build the prism and then record the dimensions and volume on their recording sheet. I also gave them the challenge of figuring out the formula. This gave my higher kids a challenge to keep them engaged. 

Reflection:

Once time was up, I called the class back to the carpet. First I had several pairs share out one set of their data. Once we had the dimensions & volume for several rectangular prisms recorded, I asked if any students had figured out the formula. After hearing several ideas, my class was able to come up with the correct formula V = l x w x h. Then we used this formula to check their work. 

Extension/Intervention:

After we figured out the formula for volume, I sent students back to their desks with a new set of task cards. This time I had them fill out their recording sheet without using the cubes to construct the prisms. The students who were still struggling with misconceptions worked with me in a small group. We filled out the recording sheets without the cubes and then checked our work by building it. 

Common Misconceptions:

I have found a couple of common misconceptions with my kids when it comes to finding the volume of a solid figure. A lot of students want to count each side of the cube as 1 unit. Another misconception is that when students look at a picture of a rectangular prism, they only count the units they can see. For kids who struggle with this objective, giving them more time and opportunities with manipulatives gives them a solid understanding that they are able to transfer to test format questions.

You can download the materials I used for free my Teachers Pay Teachers store. Just click on the picture below: