Updated 2018 – Spreadsheet that will graph 20 trials, along with the Density of Water

Purpose:Change the density of the film canister so that 97-99% of the canister is suspending under water (very SLOWLY floating from the bottom to the top of the tank).

Materials:

Film canisters with secure lids – one per student

small objects of different masses – pebbles, pennies, etc…

lunch tray to hold materials for each group of students

Set up hints – students prep items at their table then come up to the tank. After dunking, dry off with towels (I just drop it onto a thick folded up towel next to the tank). I have a bank of TBBs set up on the side of the classroom – students find the mass on their assigned TBBs then record results. Repeat trials. Towards the end of class, students enter all their data into the spreadsheet then I give them the volume of their film canister. Depending on the type of film canister, the volumes are about 39-41 mL. Confirm with a large graduated cylinder or water displacement tank.

For more details about this activity, please see my original post. If you have used this lesson with your students, please let me know, you can post it on my Twitter feed @MSScienceBlog

For this activity, I used the set of density blocks from Flinn Scientific. Each group of students had 6 blocks made of the same material. Their challenge was to identify the material using their measurement skills to calculate the mass, volume, and density of each block. This activity also reinforced the concept that the density of an object is constant.

Provide each lab group with an assortment of bottles

Students will arrange the bottles from lightest to heaviest by making observations

They will record the order of the bottles and their contents with #1 as the lightest and #10 the heaviest on their handout

my groups used 9 bottles, but there is room on the handout for 10

Using the set of masses, they will estimate the mass of each bottle by holding a bottle in one hand and a mass in the other hand, recording their estimations on the handout

Procedures – Part 2

Students will transfer their estimation to the back page

Using the TBB they will record the actual masses of the bottles

Then they will rank the bottles from lightest (#1) to heaviest (#10) and compare their estimation to the actual masses. How close were the estimations to the actual masses? Did they place the bottles in the correct order?

Results

Bottle #

Mass (g)

Bottle #

Mass (g)

Bottle #

Mass (g)

1

126.9

14

281

27

192.3

2

72.9

15

336.5

28

330.9

3

29.6

16

223

29

465

4

438

17

70

30

195

5

202.1

18

36.43

31

59.1

6

166

19

185

32

168.8

7

63.1

20

88

33

33

8

301.5

21

140.1

34

100

9

224

22

49.1

35

402.5

10

610+

23

73.3

36

187.1

11

67.1

24

54.9

37

318.4

12

251.8

25

27.5

38

13

410.1

26

406

39

You can also use these bottles as part of your density unit, see my blog entry for more information.

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!

Further Exploration

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:

Rocks/pebbles

laundry detergent – liquid or powder

paper clips

paper shreds

crayons

marbles

flour

bread crumbs

coffee beans

beans

different shapes of pasta

pom-poms

pop corn kernels or popped

Lego pieces

salt

dish-soap

beads

yarn/string

etc…

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…

Calculators

Procedures:

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)

Here is nice video that gives a general overview on how to use the TBB:

3/28/18, updated again 10/7/18

OHAUS is no longer providing the free online tutorial for this activity – I will post alternatives as I find them.

Reading a Triple Beam Balance Worksheet (pdf) and Ohaus website (link)

This is a great interactive tutorial from Ohaus (link). Using the tutorial prior to using the triple beam balance in class significantly improved the student’s understanding of how to find, read, and record the mass of an object to the nearest 1/10th of a gram.

For the tutorial, each student works at their own pace and is given immediate feedback for each answer they submit. The problems are randomly generated and each student has a slightly different experience, as opposed to having each student answer the same set of problems. Students will also review place values for 100s, 10s, 1s, and 1/10ths. (Values for the 100ths place may appear in the answers, but students will only be assessed up to the 10ths place)

Next Generation Science Standards, Science and Engineering Practices (SEP)

(SEP2) Practice 2 – Developing and Using Models

(SEP4) Practice 4 – Analyzing and Interpreting Data

(SEP5) Practice 5 – Using Mathematics and Computational Thinking

Above is a photo of a 4-door foldable for the three density related formulas: D= M/V, V= M/D, and M = VxD. The 4th door has step by step instructions on how to solve a word problem. Along with the formulas, inside the foldable are 3 practice problems, and a few notes about mass, volume, and density.

On the right side of the notebook are practice problems. Students have to determine which formula is needed, set up the problem, solve, and add the correct units. They can refer to their foldable for the formula and how to solve the problems. I have the students close the flaps for the known values. For example, if the problem states the Density and Volume values, they close those doors on the foldable leaving the Mass flap open, since it is the missing value. That is formula they will then use to set up the problem correctly and solve.

My main goal for this lesson is having the students choose the right formula, set up the formula by plugging in the known values (this is a step that the kids don’t feel the need to do/show as part of their work), and adding the correct units when done. Some students may have a little difficulty with multiplying or dividing decimals and rounding to the 100ths place, so I usually go over that before we begin by modeling a few problems with them.