By Kelly Haarala | Instagram: @supersassandscienceclass
What student can’t identify with the idea of having a cell phone in their pocket? Almost none. Most students rely on that little lithium-ion battery in their phone without even realizing what it is or why it is important. As we become more and more reliant on mobile devices and portable electric power, lithium-ion batteries are present in our lives. But are they safe? And how do we know?
“Don’t some of those explode?!” exclaimed one of my eighth graders, as soon as they saw my bell ringer asking if hoverboards were safe. Thanks to a handful of widespread news stories about hoverboards exploding in homes, this real-life connection hooked my students on the idea of how and why portable electrical power, and more specifically lithium-ion batteries, are relevant to their lives.
The “UL Xplorlabs Portable Electrical Power™” module gives middle school students the opportunity to explore a topic so relevant to them in an authentically engaging way! Students navigate through a series of learning opportunities focused on lithium-ion batteries and are finally given a task to create an enclosure for a hoverboard battery pack.
UL Xtreme Test Zone
As we started digging into elements of battery safety and testing, the UL Xtreme Test Zone introduced and scaffolded these concepts so students were prepared to move forward through the module.
Students were guided through a series of interactive screens with engaging and age appropriate videos detailing battery components, thermal runaway and engineering practices. As they clicked through each topic, they built on their knowledge of battery safety and engineering.
As we started digging into elements of battery safety and testing, the UL Xtreme Test Zone introduced and scaffolded these concepts so students were prepared to move forward through the module.
Students were guided through a series of interactive screens with engaging and age appropriate videos detailing battery components, thermal runaway and engineering practices. As they clicked through each topic, they built on their knowledge of battery safety and engineering.
Xtreme Tests
Then students end up on a screen where they can choose an Xtreme Experiment (along with a warning at the bottom that says, “Don’t even consider trying this!”… . Because they’re in middle school!). They look at four tests: the crush test, the blunted nail test, the projectile test and the overcharging test. Each one shows footage of real tests where lithium-ion batteries were pushed to their limits in extreme conditions.
Let me tell you. Your kids will love this. There is no better way to get middle school students to buy into something than creating an explosion, and this element of the module does just that! There were suddenly exclamations of excitement and students looking over friend’s shoulders to watch the tests again, even though they just watched it on their own laptop. I overheard one of my students saying, “This would be a really cool job!” As a teacher, that’s something I want to hear!
Give them some ownership
Finally, they run some virtual tests of their own. First, they perform a drop test, then they overcharge the hoverboard. In both of these tests, students control the variables to see how much or little damage a battery can withstand before it becomes dangerous.
The UL Extreme Test Lab was the foundation for the rest of the Portable Electrical Power module. One student said, “Batteries are very susceptible to damage and must be protected. They are also very dangerous to us when they are damaged.” This understanding is key to moving forward as they investigate potential damage to people next.
The Bologna Test
Fair warning … this lab is a little bit gross but oh, so cool! Students just investigated what happened to batteries placed in extreme conditions, and clearly, we need to protect people from the potential dangers of batteries.
But do we need to protect batteries from people?
We use small button batteries every day, from a garage door opener to an Apple TV remote. If these batteries were not enclosed well in their device, would they cause harm? As students begin this investigation, I asked them to keep the idea of enclosure safety on the front of their minds. What are the risks if batteries are not secure in their enclosure?
Students investigate this firsthand with bologna, a battery and contact solution. A slice of bologna acts as a throat. Simply placing the battery on the bologna and adding some contact solution (acting as saliva), students watch the damage a battery can do to an esophagus.
“EEWWW, it smells!”
“Ohhhh no way!! It’s sinking into the bologna!”
As the test progressed, a chemical reaction burned the bologna. Heat was produced as well as a green bubbly substance eroded the bologna slice.
One student said, “This part of the test made me realize the importance of battery safety because I saw what it did to the bologna, and it was really bad. Enclosures for batteries need to be harder to open so little kids can’t easily open one.”
The Tensile Strength Test and Design
At this point, students have learned about battery testing and consequences of improper battery usage. Now they get to transfer this knowledge to start building an enclosure for a hoverboard battery pack! Their goal was to create an enclosure that protects the battery from damage and protects the person using the hoverboard from heat emitted by the batteries.
As they begin engineering their enclosure, they have a few requirements they had to meet. These requirements included:
- Dimensions of the enclosure were eight inches by three inches by three inches
- Protect the battery pack (inside the enclosure)
- Hold up a can of soup weighing 16-18 oz. for more than 2 minutes (representing the weight of a person.
What material should they use?
Tensile strength is a material’s durability. My 8th graders tested several types of material’s tensile strength to determine what would best help them meet the requirements for their enclosure. They looked for material that held the weight of a soup can without stretching or ripping.
Most groups settled on using cardboard for their enclosure and used various materials to protect the battery pack inside, including cotton balls, bubble wrap and other various materials they asked permission to use.
“We used the cardboard because it was very sturdy and withstood the weight of the soup can. The cloth and bubble wrap helped protect the batteries inside the enclosure,” one student reflected.
This phase is completely student centered. They were in charge of engineering the enclosure, and I’ll have to say … I was impressed with some of their designs. One group was having a hard time keeping their cardboard sturdy (someone bent it!), and they stuck toothpicks into the corrugated middle of the cardboard to create more stability!
Misconceptions
I encountered a huge misconception in this part of the module. Students wanted to be sure the enclosure did not keep too much heat inside of the enclosure so the battery didn’t overheat and lead to thermal runaway. Several groups simply wrapped the batteries in fabric and used the batteries themselves to support the soup can. I had to remind them that while it was important to make sure the battery doesn’t overheat, they also wouldn’t want to ride a hoverboard that burned their feet. Plus, the weight on the batteries would cause a whole different set of problems!
The Thermal Test
Finally! The last phase of this module is here and students can apply what they have learned and engineered in this final round of tests! Remember—they have to create a safe enclosure for the batteries that prevents too much heat from escaping.
Groups of students use instant hand warmers to simulate battery heat. (Pro tip: You can use the same hand warmers for multiple classes. They stay warm forever. Also, open those packages about an hour before your first hour class. They take a bit to heat up!)
First, students need to take the internal and external temperatures of their enclosures to create the control. Next, they’ll insert the hand warmers into their enclosure, put the soup can on top and wait for five minutes. This gives the battery pack plenty of time to heat up their enclosure. Then, they take two temperatures – internal and external. If the internal temperature increases by more than five degrees Fahrenheit or the external temperature increases by more than 7° F, the enclosure design fails and students have to redesign and retest!
Retesting
Retesting is such an authentic part of the learning process. Of course, students want to get it right the first time! I heard so many good conversations about how they began changing their original designs to meet the requirements.
As I was walking around the classroom, I asked one of the students what the result of her group’s retest was. “Our first internal temperature was 9 degrees higher. We took out all the cotton balls and retested. The first internal temp was 86. After we redesigned, the temp was 77.2.”
What are you waiting for?! (heading)
Seriously? What are you waiting for? This authentic learning opportunity is an incredible resource for your students to be introduced to real world engineering opportunities. Then they got a chance to apply those ideas and collaborate with their peers, bringing their ideas to life. Following through to see how their enclosure held up to the requirements was a great experience for my students. One student said he, “enjoyed building the design for the heat test because it was pretty fun, and I wanted to see if our model really worked.”
The best part – the Portable Electrical Power Module is completely free! Everything is written and put together for you. Check it out and use this module in your classroom! Your students will be challenged and authentically engaged.