Inspiring Students with a Tin Man #mathed #mathchat

The time of year came when students were ready to study surface area. How was I going to make this interesting and real? The students in my classes were itching for geometry. The common chant heard, “I love geometry!” I had to make sure I kept this level of excitement within the students.

As I began searching through my vast amount of resources, I couldn’t quite find the “best fit.” This led me to Twitter. Reaching out to my PLN, a fellow math teacher had shared a lesson she did with robots. This sparked the idea of creating a “Tin Man”.

The task for students was to create their own version of the Wizard of Oz’s Tin Man. As they created groups of 4 and 5 students, they were given further direction. All groups had to use at least one sphere, one cone, one cylinder and one rectangular prism in the creation of their Tin Man. The final product had to fit on a school desk and had to stand on its own when complete. The planning began, as did the excitement for the task.

Groups brought in objects from home such as cereal boxes, wrapping paper tubes, and Styrofoam spheres. Birthday hats and unused Snowcone wrappers were used for cones, although some groups used nets to create their own cones. When the final designs were ready to be implemented, students then began to question how they were going to make it “silver.” Great question!

Each Tin Man was to be covered with aluminum foil, “tin.” Students had to work together to determine the amount of “tin” needed for their Tin Man by determining its surface area. This meant measuring, calculating and using formulas correctly. This also meant students had to recognize which areas needed to be covered and which did not. For instance, when a cylinder was connected to a prism the circular area would not need foil. It was great to see students then determine that this area then had to be account- ed for twice. Do you know why?

Precise measurements and calculations would lead to a relatively precise amount of foil needed to cover the Tin Man. Once the total surface area was determined, students were given a roll of foil to cut the needed amount. Important to know here is that students were only allowed to cut once. Whatever they cut for foil was what they needed to use. They could not come back for more. They also could not throw away extra.

The cutting of the foil turned out to be another task. Students were allowed to use any unit of measure for their work. As they approached the roll of foil some realized that their measurements in centimeters or feet needed to be converted. The second challenge came when they realized the number which they had was in square units and they needed to determine the correct linear measurement, or length, before cutting the foil.
A great deal of discussions happened around the rolls of foil.

As groups realized they needed to divide their calculated surface area by the width of the foil, the rolling of the foil began. This step proved to be telling for some groups. They knew that as soon as the foil was cut, that was what they had to use. Using estimation skills, some were quick to realize that they were going to have too much or too little foil. For some groups, this meant going back to check measurements and calculations.

When groups made the official cut of foil they were on their way to covering their Tin Men, another challenge. The piece of foil, which was cut, was rectangular in shape. Students had to determine how to cover the surface area of the Tin Man. Some areas were going to be covered with scraps of foil and not full sheets. Appearance of the Tin Man was important, as it was a part of their grade.

The grading of the Tin Men was easy. Students were graded on calculations, precision, quality, and collaboration. Each student had to submit a calculation sheet showing the formulas and mathematics used to determine the surface area of the Tin Man. Precision was determined based on the precision of the foil. These two grades were math grades where quality and collaboration were responsibility grades. Students earned their individual grade.

The final products varied in quality and precision but they were all displayed. Students were proud of their efforts and even named their Tin Men.

As a teacher, I felt I had achieved my goals of making the lesson interesting and real. I was looking for students to work with surface area and hadn’t thought of the other aspects of mathematical learning which students encountered. The best aspect was reading student reflections at the end of the year. Students loved this project despite the challenges and hard work they encountered. Students even spoke about the Tin Man Project during the school’s Day of Learning, expressing how proud they were in persevering, and collaborating to complete a very challenging task.

Getting the “right answer” isn’t the way to inspire students.