I updated my Dunkin’ for DensityLesson for 2016, I use this lesson with my 6th graders as part of our unit on properties of matter. I wanted it to be more data driven and have them analyze the data from all of their trials, and then compare their data to their classmates. I changed the objective to:
Change the density of the film canister so that 90-99% of the canister is suspending under water.
This is one of my favorite activities from our minerals and mining unit. It takes about 1 whole class period to explain the activity, collect data, eat the cookie (& crumbs), and clean up. We discuss our results the next class and determine who made the most profit.
When determining the value of the chocolate ore, I have the students place their chocolate pieces close together in one area of the map. When they are done, I go around and circle the area of chocolate and give their chocolate a rating. They count the number of boxes their chocolate covers and enter it into their spreadsheet.
If there are crumbs attached to the chocolate, I call that ‘slag’ and it lowers the value of the chocolate ore. This leads to a great discussion afterwards when we compare the profits and talk about land use. Is it better to get out as much chocolate as you can, even if you get a lot of slag, or is it better to remove just the chocolate even though you will have less in the end? How is this similar to coal mining? Diamond mining?
Demo & Discussion – For this part of the lesson, students will not handle the bottles, they will answer discussion questions based on their observations only.
Share observations about the bottles.
What do the bottles have in common?
What is different about the bottles?
What do you think the original contents of the bottle were?
What phases of matter are shown?
Are any of these bottles empty? Explain.
Do all of these bottles have air in them?
Which bottle has more air in it: Cotton Balls or Water? Explain.
Which bottle is filled the most? Least?
Which bottle has has the most ‘stuff’ in it? Least?
Which bottle is the heaviest? Lightest?
How would you order these bottles from lightest to heaviest?
Estimate the mass of each bottle in grams.
Which bottle is the densest?
How would you arrange these bottles from least to most dense?
Which of these bottles can have more of the same ‘stuff’ added to the inside of the bottle? Explain.
Which bottle(s) would float in a tank of water? (I do this at the very end of the lesson with everyone at the sink)
Hands On Exploration
Each group will have one set of bottles or take turns using the demo bottles and sharing their findings.
Using a triple beam balance, the volume of the bottles, and a tank of water, answer as many of the questions above as you can. (for our calculations, we use the volume of the bottle’s original content (500 mL of sport drink) to give us an approximate density, not the actual density – for comparison purposes only)
How did your findings compare to your observations and predictions?
Dunk tank – time to find out which one will float!
Give each group of students a new set of bottles (ones that they have brought in from home) and have them make observations, predictions, and density calculations.
Additional Bottle Ideas:
laundry detergent – liquid or powder
different shapes of pasta
pop corn kernels or popped
Have each student bring in a bottle from home filled with the contents of their choice so that you have enough bottle to compare. Match similar bottle shapes/sizes together for each group or match similar contents in different sized bottles for comparison.
You can also use these bottles as part of a Triple Beam Balance Activity (blog entry).
This is a wonderful problem solving and hands-on activity to use as part of your density unit. The students enjoy the challenge and have a solid understanding of density after completing this activity. Even though students quickly figure out how to make the canister float and sink, making the canister suspend is pretty challenging and requires a lot of trial and error and problem solving.
To qualify as suspending, the film canister needs to float just under the surface of the water, with a small portion of the top just breaking through. How I also verify that it is suspending is by pushing the film canister to the bottom of the tank, if it comes up very slowly to the surface, it counts – if it comes up quickly or stays towards the bottom, it doesn’t count. Students then need to figure out that if it comes up too quickly, they need to add to the mass, if it comes up too slowly, they need to remove some of the mass. It will take several tries to get it just right.
one canister per 2 people works well, they can reuse the canisters if you don’t have enough to give each set of lab partners 3 canisters
if they reuse the canisters, be sure that they find the mass before they empty the contents
An assortment of small objects such as pennies, paper clips, stoppers, small pebbles, etc…
Introduce the Dunkin’ for Density Challenge – their goal is to make the film canister float, suspend, and sink by placing contents inside of the film canister.
Many students will say that the canister will float with nothing in it, but they must place a few objects in it for it to count 😉
On a side note, a mini history lesson on film and cameras is fun to discuss since most students have never used a camera that used film
Explain the procedures, review how to use the TBB, note that the film canister must seal completely and be air tight so that water doesn’t enter, and also demonstrate how to use the dunk tank properly and to dry off the canister before finding the mass.
Do not give the students the value for the volume of the film canisters until they have collected their data. If the students know the volume of the film canister, they may figure out the mass needed to make the film canister’s density close to 1.0 g/cm3.
The value is approximately 39 mL or 39 g/cm3 – verify with a large graduated cylinder that the film canister can fit inside of – or use an overflow can to find the volume (link).
I will give the volume to each set of lab partners individually and ask that they don’t share that information with the class.
Once students have calculated the density, collect class data on a spreadsheet projected on the board/screen.
Discuss results – why did the film canister float, suspend, or sink in the tank of water? What relationships did you notice?
For more lessons related to the Properties of Matter, click here (link)
The original worksheet(pdf) for this activity is from Project Archaeology (link)
I also created Google Slides for this activity (Public)
Students often have difficulty distinguishing between observations and inferences, they often combine the two into one statement. For example, when asked to make an observation using the image above some students may say: “The boy fell into the water because the branch broke.” Another student may say: “The goat pushed the boy into the water when he was trying to pick up his sailboat.”
We then discuss the difference between the facts and the “story” that goes with it. The facts are our observations and the story is how we piece the facts together, or our inference.
a boy is in the water
a goat standing next to the water
a broken tree branch
a sailboat is floating in the water
The branch broke when the boy was sitting on it, and he fell into the water.
The goat butted the boy into the water when he was picking up his sailboat.
After defining and discussing the differences between observations and inferences, students will have a chance to work with their partner to practice identifying and classifying the statements related to the image of the boy in the water. Once everyone is done, as a class, we then discuss each statement and confirm each as either an observation or inference.
Use the picture of the boy in the water to determine if the following statements are observations or if the statements are inferences. Place an “Inf” in the blank for inference and an “Obs” in the blank for observation.
____ The boy is in the water
____ The weather is cold
____ The tree branch is broken
____ If the boy crawled out of the water, the goat would push him