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Inquiry Density Challenge
As we finish up the school year, I decided to give my 7th grade students a challenge. We've learned about density and how to calculate it. We also have taken time to experiment with how various densities allow some objects to float more easily than others. One activity we did was determining which liquids were densest and layering five liquids in order (densest at the bottom to least dense at the top.)
Today's challenge involved an empty 35mm film canister for each student. I had large plastic containers at the front of the room. Each container had water in it. (Total depth was about 15 cm.) I put a drawing of the containers with water in them on the board. Added to the drawing were three different 35mm film canisters. One was at the top of the water, one at the bottom of the container, and one suspended in the middle.
I asked students if we placed their empty canister with the lid on it into the water, where would it go. All students said it would float at the top. I then asked if we filled the 35mm canister with sand and put the cap back on what would happen. They quickly responded with it would sink to the bottom.
I told my students their challenge was to figure out how to get their 35mm film canister to float under the surface and NOT touch the bottom of the container. Several of the gifted students in the room smiled quickly and made comments about how easily this would be done. I allowed students to use ANY materials they could find in the room to fill up their 35mm film canister. Some things that were tried included pencil shavings, torn paper, tissue paper, coins, clay, a watch, both rubber and cork stoppers, as well as crayons. I was excited to see how many students were engaged and excited by the assignment. No one complained about doing school work on the next to the last full day of classes. The gifted students began talking with friends about what they were trying when it was discovered to be more difficult than planned.
I really enjoyed seeing students challenged this way. Each student seemed to want to succeed and was willing to share what they had discovered with a neighbor. I saw collaboration reaching new heights in the room. No one completed the task, but several asked if they could work on it at home and bring in the 35 mm film canister tomorrow:). Perhaps I succeed when students ask to do homework without being assigned to.
By the way - I found some local film developing companies keep these empty film canisters and will just give them to you. One source for me locally has been my local WalMart.
Let me know if you try this activity and how it works out for you.
Today's challenge involved an empty 35mm film canister for each student. I had large plastic containers at the front of the room. Each container had water in it. (Total depth was about 15 cm.) I put a drawing of the containers with water in them on the board. Added to the drawing were three different 35mm film canisters. One was at the top of the water, one at the bottom of the container, and one suspended in the middle.
I asked students if we placed their empty canister with the lid on it into the water, where would it go. All students said it would float at the top. I then asked if we filled the 35mm canister with sand and put the cap back on what would happen. They quickly responded with it would sink to the bottom.
I told my students their challenge was to figure out how to get their 35mm film canister to float under the surface and NOT touch the bottom of the container. Several of the gifted students in the room smiled quickly and made comments about how easily this would be done. I allowed students to use ANY materials they could find in the room to fill up their 35mm film canister. Some things that were tried included pencil shavings, torn paper, tissue paper, coins, clay, a watch, both rubber and cork stoppers, as well as crayons. I was excited to see how many students were engaged and excited by the assignment. No one complained about doing school work on the next to the last full day of classes. The gifted students began talking with friends about what they were trying when it was discovered to be more difficult than planned.
I really enjoyed seeing students challenged this way. Each student seemed to want to succeed and was willing to share what they had discovered with a neighbor. I saw collaboration reaching new heights in the room. No one completed the task, but several asked if they could work on it at home and bring in the 35 mm film canister tomorrow:). Perhaps I succeed when students ask to do homework without being assigned to.
By the way - I found some local film developing companies keep these empty film canisters and will just give them to you. One source for me locally has been my local WalMart.
Let me know if you try this activity and how it works out for you.
Add a Comment
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Comment by Glen Westbroek on July 6, 2009 at 8:54am - I like your idea of using empty plastic soda bottles with tops cut off - yet another way to save money. And I also like the extension to have students calculate water density.
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Comment by Kevin Taniguchi on July 5, 2009 at 11:59pm - 1 L plastic soda bottles with the tops cut off also work for water containers. Remember to get lots of paper towels for this activity. Density is very fickle - I told my students to try to calculate the density of water from this.
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Comment by Glen Westbroek on May 30, 2009 at 12:00pm
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I do not have a large sink - I have some large semi-clear containers I use. Like you, I worry about losing 35mm canisters soon due to digital cameras.
Great reminder of pop rockets - double use.
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Comment by Kevin on May 30, 2009 at 7:26am -
That sounds like a great hands-on activity. I also get my film canisters from WalMart but I wonder how many more years before they are no longer made due to digital cameras.
Glen, do you have a large sink to do this activity? I think one would need a sink or a few aquariums to do this activity.
When your done with the canisters, you can make pop rockets with them by putting a piece of alaka-seltzer and some water inside.
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Comment by Glen Westbroek on May 27, 2009 at 11:09pm
- I've found there is NOT a magic formula. It seems to be a challenge to try to get "neutral density." Students LOVED the challenge and were more engaged than on other activities/labs I expected they would enjoy more.
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Comment by mr. f on May 27, 2009 at 10:45pm
- great! is there a magic formula?
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