This project / lab is suitable for students in third grade up through eighth grade, depending on how you present it to the students and what aspects of the project you include. I used it for my seventh grade classes and it was extremely successful with that age group.
The start of the school year is an exciting time for both students and teachers alike. One of the best aspects of being a teacher is that each year brings the ability to wipe the slate clean and try totally new ideas and projects. Some of them work and... well... some of them crash and burn. I'll tell you right now, this one did not crash and burn. It started off with a quick question I posed to my students, "Have any of you done the lab in elementary school where you build a aluminum foil boat and see how many pennies it can hold while it floats in water?" The number of kids who raised their hands was impressive. I'd say that 3/4 of the kids had already done that lab, which got me thinking.
All of this stemmed from my desire to create a new start of the school year project that allows us to collect quantitative data and qualitative evidence. I wanted my students to get immersed in the real ins and outs of science right at the start of the year, all while having a ton of fun.
The goal of this project is for the students to design and build an aluminum foil boat out of a 6"x10" piece of foil that can successfully carry 10 pennies down what I call the "Stark Raging Rapids" which is basically a small in-class river I made from a scrap piece of PVC pipe, some rocks, and a couple of pumps. The students first are given the challenge to make a boat that can hold as many pennies as possible with the 6x10 foil. They test them out in small "ponds" of water made from recycled salad containers. After they get a grasp on buoyancy and what makes a boat work they then have to alter their design so that it will be able to make its way down the river course carrying at least 10 pennies. We not only collect qualitative details during the testing but also the speed the boats move by determining the time it took for them to travel from the start to their ending position.
I'll explain the building of the river system along with the steps I took to implement the lab. I am also sharing the lab documents I created for this project.The majority of the materials I used were reclaimed / recycled, making the project super affordable and fun to build. I hope you enjoy!
To Build the River Tube
(1) 10' x 4-1/2" PVC pipe
Small, smooth rocks
Hot Glue / Hot Glue Gun
Jig Saw with fine toothed blade
Scrap foam board / insulation
(1 - 2) Small Water Pump (a fish tank pump works too)
(5') Vinyl tubing that will fit over the pump nozzle
(2) 5-gallon buckets
To Build the Boats
(A whole bunch) Aluminum foil cut into 6" x 10" pieces
To Test the Boats
(Piles of them) Pennies
(One per group) Plastic containers that can hold water to test the boats
To run the boats down the river
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Step 1: Cutting and Creating the River Tube
My neighbor had a few left over pieces of 4-1/2" drain pipe in his yard so there was no need for me to purchase the tube. I am sure they are not expensive at one of the big box stores but if you can score something for free on Craigslist you too will have that satisfying feeling of building something effective on the cheap.
Although, I do have a table saw and a bandsaw I decided to use a jigsaw to cut the pipe down the middle to make two 10' halves. I felt this was safer and required no jigs. I used a chalk line to snap a line on both sides of the pipe and then used a fine-toothed jigsaw blade to make the first cut. Turn the blade speed on low (if you can) to help prevent the blade from heating up too much and melting the PVC together and then cut along the long line. Flip the pipe over and cut the other side and you will have two moderately even 1/2 tubes. I took the uglier of the two sides (had some holes and bruises) and cut it into 10" sections so the kids could use these to help form their boats to fit the river bottom.
I had some leftover 1" foam insulation board kicking around so I used that to create both the upper "mouth" of the river and the lower "catch" so that the boats didn't get sucked down the tube at the end of the course. I used clear silicone caulk to adhere the foam to the PVC pipe and made sure that the lower "catch" was low enough to prevent some of the more narrow boats from heading on an unwanted adventure while still allowing the water to easily exit the bottom of the tube into the bucket.
Finally, I built some very simple supports to help hold the pipe up at a 30 degree angle. I used scrap lumber and used a piece of the pipe to mark out the arc that will cradle the river tube in place. Take a look at the pictures to get the main idea and if you need more details please put a note in the comments.
Step 2: Make a River Bed!
I washed out the pipe and then dried it first. After it was completely dry I used a number of smooth rocks I collected to create the "features" and "obstacles" in the river. I put rocks along the walls to help channel the water when the pumps are running and then used wide flat rocks to make rapids and "drops and holes" for the little boats... this part was a lot of fun! I used hot glue to affix the rocks in place and then used a bunch of hot glue to help smooth out the fronts of the rocks so there would be smoother transitions as the boats traveled down the tube. After everything was all set I used a piece of masking tape to make a simple measuring tape that traveled down the length of the tube. I used a meter stick to mark off each centimeter from 1cm to 265cm. This will be used to measure how far the boats made it down the rapids before capsizing or getting stuck.
I made one area you can see in the video that had a larger rock creating a "Class IV" rapid with a nice little drop and hole at the end. Since there wasn't a very smooth transition between the pipe and the rock I used a bit of aluminum foil hot glued over and around the rock to aid in the ramping effect. Overall, you will have to tinker around with what works best and the beauty is that you can change it up the following year if you use a flat head screwdriver to pry up the rocks. Ultimately you want to make sure that the well-designed boats can pass through and over the rocks. You will want to make your own to test out prior to starting up the lab.
Step 3: Make the River Rage
In making this entire project extraordinarily inexpensive, I tried using any materials I could dredge up to make it work. I started with an old fish tank water pump which, after some disassembly and elbow grease, I was able to get pumping again. The pump made a nice dainty stream down the pipe but we needed more flow. This is where my one and only purchase had to come in. I spent a walloping $18 on Amazon for the pump pictured to the left of the fish tank pump. With the two pumps combined we had a significantly raging torrent of water heading down through the pipe. I used two buckets to recycle the water from mouth to outlet. I was thinking of using one bucket at the bottom with the pumps pushing water back to the top of the river but to get the timing / flow down perfect would be really tough and honestly not worth the effort. Once the bottom bucket fills up, the top bucket is empty, I turn off the pumps using a power strip and then dump the water from bottom bucket into top bucket. Takes a bit more time and gives you a workout throughout the day, but works swell. To make sure that the water was going into the bottom bucket and not all over the floor I used a scrap piece of my shop dust collection hose pushed over the half pipe. The pipe was set up on the two stands and I used a spring clamp to hold them in place, just in case they got jostled by the students when they were observing / placing boats in the water.
Now that you have everything ready to go, it's time to get the students involved!
Step 4: Lot's of Aluminum Foil
You will need a fair amount of aluminum foil for this project. I used approximately one roll for four seventh grade classes. I found that the best way to cut the foil was to use a sharp pair of scissors and to cut through multiple sheets at a time. Before you unroll it you can at least mark the middle of the roll with the blunt side of the scissors. Simply push the back of the scissors to the roll and rotate the roll leaving a nice indent in the roll to mark the 6" center point. I usually will cut strips that are five feet long (the length of my tables) and then I mark off 10" intervals and cut them all in bulk. The aluminum does somewhat get crimped together but with careful enough hands they pull apart with very little problem... in other words, don't let the kids pull the foil from the stack or you'll have lot's of ripped pieces!
Step 5: Penny Haulin' Boats!
To start off the lab we spend a part of a class period exploring what designs work best to hold the most pennies. This is prior to the students seeing the river system. Student remember this activity from previous science classes they might have had in elementary school or from just playing around at home. The only constraint I give them is that they need to make their boat out of a 6"x10" piece of aluminum foil. I give them two sheets of aluminum foil to work with. The first to prototype their idea and the second to make their final design to present to the class. I have the students use the engineering design process I teach in my class to help them identify the problem and develop a solution. I use the last two slides in this presentation for this section of the lab. I have students complete all of their work in their notebook so we can discuss and share the results as a class at the end of this first activity. Depending on the age of the students you can incorporate more direct information about buoyancy, displacement, and the specific design of boat hulls. There are lot's of connections and extensions that can be made.
The kids have a blast with this first component of the lab and it's a great way to get them prepped for the next section. I particularly loved how so many of them used ideas from this initial design in their final design for the raging rapids... that's engineering!
Step 6: Can Your Boat Survive the Raging Rapids?
Now that the students have a solid understanding of what works best to hold as many pennies as possible they need to modify their design and make it best at carrying a set amount of pennies through the "Stark Raging Rapids". We spent some time discussing what kind of designs might work best to accomplish the task and we also discussed how the previous designs might no longer be valid due to additional constraints on the new design. I use the same presentation we initially used for the first activity but this time I start right at the first slide. This gives the students the main goal, and the constraints and requirements for the project. I also distribute the student data sheet so that the students can use this while they work on the lab. For this section of the project I allow the students to use multiple pieces of aluminum foil until they feel they have created their best possible design. They are welcome to test them in the pools of water and I also fire up the raging river so that they can test their boat down the river without any pennies in it. It's important that they follow through with the engineering design process, so I encourage them to work on the lab sheet while they build and test their boats. Once the boats are built and the entire class is ready, you can then test the boats so the entire class can see the results. You will need a stopwatch so that you can time how long it takes the boat to make it to the finish, or at least to where it gets stuck. The students will then enter in the data for the speed with and without pennies in the boat. This alone leaves a ton of room to incorporate more physics into the lesson if wanted. The final two parts of the lab sheet ask for the students reflect back on the results and determine how they would revise their design to make a boat that works even better. I give the additional challenge for boats that make it down the rapids with ten pennies to see if they can carry twenty-five pennies. This is a blast and the kids cheer on each other's boats during the tests.
I can honestly say that this lab truly nails home the engineering design process in the classroom while giving the kids the opportunity to explore the ideas of displacement, buoyancy, speed, and model building. There are multiple avenues you could take to extend the lesson and make additional connections. Best part is that, as a teacher, the kids are extremely engaged and the initial outset for materials is minimal. I hope you enjoy the lab and please ask any questions or post your experiences with it in the comments. Happy building!
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