Rainbow Lab

One of my favorite activities is the Rainbow Lab.  This is a great activity for practicing their measurement skills, ability to follow directions, precision, working as a group, following correct lab procedures, equipment use and identification, solutions, mixtures, physical changes, problem solving, etc… It’s chock-full of stuff.

What I also love about this lab is the importance of not fudging your data, and reporting what actually happened in the lab, not what you think should have happened, or covering up “mistakes”.  If one of your lab partners spilled the yellow, you have to account for the loss of the yellow in your data, how it affected your measurements, etc. What do we do if someone breaks a test tube? What if I spilled something onto my clothes or skin? How can I avoid contamination of my colors when using only one graduated cylinder?

To set up this lab, I use a concentration of 5 drops of food coloring per 100 mL of water. Each group gets one set of test tubes, a beaker for waste water, a beaker of clean water, a pipette, 25 mL graduated cylinder, 3 flasks, and stoppers. The stoppers are important because if a group does not finish the experiment in one class and has to continue the next day, it prevents evaporation – which would alter their data. 

Before I start a lab, we always meet as a group, usually around a table with one set-up.  I explained the lab, and talked about what a solution is, and what the solutes and solvents were for this lab.  We talked about how this was a homogeneous solution, the food coloring does not settle out over time. 

I stress the importance of avoiding contamination, or the “Big C”. We don’t want colors mixing together and making muddy colors.  I show them how to rinse out their graduated cylinder between measurements, and dumping the “dirty” water into the waste water beaker.  I show them how to twist the graduated cylinder as they pour, this cleans the sides of any food coloring residue. I also reminded them about the meniscus when reading measurements.

When completed, the measurements for each test tube should read A-F: 10, 11, 10, 11, 10, 11 with a total of 63 mL.  They also have to account for having more or less than 63 mL, where did the extra volume come from if they went over? Where did it go if they were short?

I don’t tell the kids how much they should have had until the next day, when we go over the analysis questions.

Handout:

• Rainbow Lab- updated for the interactive notebook

 

Dunkin’ 4 Density Activity

We completed the “Dunkin’ for Density” activity today, collected our data, entered it into excel, and discussed our findings. 

For this lesson, the kids had to make 1 film canister float, 1 film canister suspend, and 1 film canister sink in water by changing their densities.  We used white/clear plastic film canisters and I calculated the volume as 39 ml or cm3 by using water displacement and a large graduated cylinder.  (The film canisters hold about 35 mL of water, in case you were wondering!)

Supplies: plastic tray, 3 film canisters per set of two lab partners, a bowl or large beaker filled with water, pennies, rubber stoppers, cork stoppers, paper clips, and bits of clay. I also had a really large/deep bowl as the “official suspend testing tank”.  Once the kids tested their suspending canister, they brought it over to be officially checked by me.

Using whatever combination they like, they place the items into the film canisters to complete the task. I only have two rules: you must have at least one item in the canister (which I forgot to tell the 1st class!) and it must be able to close and seal tightly so no water enters the film canister. The floaters and sinkers are the easiest to do and the kids figure those out pretty quickly. But I am very picky about my definition of suspend and it drives them nutty!  In order to qualify as a suspender, the film canister has to touch the bottom of the bowl when I tap it, and then float up slowly until it is near the surface of the water. Only a small part, if any, may rise above the water line. This is a great problem solving activity and after a few tries, they usually get just the right combination of stuff inside their film canisters to make the density very close to 1 g/cm3. (For this to happen, the mass ends up being close to 39 g,)

Once they have completed all three tasks, they use the TBB to find and record the mass into their notebooks. (Tip – make sure the film canisters are dry before they use the TBB) (Tip #2 – have them find the mass of an empty film cansiter before they begin dunking.)  Using the formula for density (D=m/v), they find and record those densities into their notebooks.  Once everyone is done, each group reports their data and we enter it into the excel spreadsheet, displaying the data on the SmartBoard. We then discuss the data and I ask the kids if they notice any patterns in the data. (Sometimes I’ll show the data from previous classes so they can compare their results to older experiments.)

After we have discussed the data, they answer the analysis questions and write a conclusion on page 41, the right side of their notebook. The one misconception that some kids may have is that the film canisters sank because they became heavier.   We talk about how yes, they did get heavier, but they sank because they became denser.

Notebook:

pg. 40 – Dunkin’ for Density

pg. 41 – Analysis: Dunkin’ for Density

Excel Spread Sheet Template to enter data  (This is a very old template, it won’t graph for some reason. If I can, I will update it.)

 

If you have completed this activity, I would love to hear from you and see your results!

Density Bottles

As an introduction to density, I do a demonstration/discussion/group activity using density bottles. They are small sports drink bottles that I estimated to have a volume of approximately 400 mL.  There are 5 bottles, each  filled with a different item: cotton, air, sand, rice, and colored water.

These are some of the questions I used for our discussion:

• “Do these bottles have the same volume?” There is some uncertainty at first, but then they quickly say “yes”.
• “Do these bottles have the same mass?” No
• “Why don’t they have the same masses?” Variety of answers
• “Which one do you think is the heaviest?” We do a survey with a show of hands then have the kids give some reasons for their answers
• “Which one do you think has the most ‘stuff’ crammed into the bottle?” It’s interesting, there is a wide variety of answers and it usually doesn’t match the answer to the question of which is the heaviest

I tell them that they will find out the answers in a minute! We watch the BrainPOP movie for Measuring Matter. After the movie, I give the analogy of standing and waiting for an elevator.  Two identical elevators open up: one has 2 people in it and the other has 15 people in it.  “Which elevator would you choose and why?” Naturally, they say the one with only two people, there is more room in that one. I ask them, which elevator is denser? The one with 15 people, of course. We then discuss that there is less empty space available in the elevator with 15 people in it.  I then relate molecules to the people in the elevator, matter that has a lot of molecules, or atoms, crammed into a given space are denser than objects whose molecules or atoms have a lot of empty space between them.

I hand one bottle to each group and have them find the mass.  We collect the data and I write it on the board. I re-ask the following questions:

• Which one is the heaviest?
• Which one has the most ‘stuff’ crammed into the bottle? (Variety of responses)
• Which one is the densest? (Variety of responses)

Now that we have the mass and the volume, we calculate the densities for each bottle.  After we collect the data, I have the kids come over to the dunk tank.  One at a time, we predict which bottles will float. We do a survey and raise our hands if we think the bottle will float.  I have one student place the bottle into the tank and we see if it floats or not. We continue until all 5 are in the tank.

The cotton, rice, water, and air filled bottles floated, the bottle with the sand, sank to the bottom. I then ask the kids “Why did the bottle of sand sink?” They usually say it was the heaviest. I then say, “But a cruise ship is a lot heavier, and it doesn’t sink? Why?”  I give them a hint, “Look at our data, what do the bottles that floated have in common?” After a while, they figure out that the bottles that floated, all had numbers that were decimals, or less than one.  The sand was over 1, and sank. I tell them the density of water is 1, so objects with a density greater than 1 will sink.

We talked about how the bottle of sand is the densest b/c it has the most amount of “stuff” crammed into the same space, and that there is less empty space between the atoms.  I tell them that the density of gold is 19.3 g/cm3, and that if this bottle was filled with gold, it would be about 19 times denser, meaning that there would be 19 times more “stuff” crammed into the same space. The next day we talked about the story of Archimedes.  We calculated how much mass the same bottle would have if it was filled with pure gold - it would be 7,720 grams!! 

After the dunk tank, we did a small group acitivty using the graphic organizer from BrainPOP.  It shows a ring, balloon, yo-yo, and pillow.  We have to categorize them according to mass, volume, and density, from highest to lowest.  We do one category at a time and I give them a minute  for each, going over the answers between each category. I liked this graphic organizer b/c it really made them think about each item and their properties.

pg. 34 - BrainPOP – Archimedes

pg. 35 - BrainPOP – Mass, Volume, Density Graphic Organzier

Volume Labs- Regular and Irregular

Over the period of about 3 days, we covered finding the volume of a rectangular prism using the formula length x width x height and finding the volume of irregularly shaped objects using water displacement.  I usually do these labs as stations labs, but decided to have the kids do the activities at their tables.

For finding the volume of rectangular prisms, I placed some everyday objects onto a tray as well as some scrap wood from our woodworking shop. Students could choose what they wanted to measure in whichever order they like.  We then compared our results.  I usually allow a  +/- 2 mm window for their measurements.

I made up some hand signals and we practiced them as a class so that the students could remember the three dimensions when taking their measurements.  It helped a lot and I saw the kids use it to orientate themselves for the 3 dimensions.

• hold your hand flat and straight on the table = length
• hold your hand sideways with your wrist bent at a 90 degree angle = width
• hold your hand straight up in front of you, fingers towards the ceiling, with your wrist at a 90 degree angle = height

What happens sometimes is that they forget which side they already measured or have trouble choosing which side will be their length, which side is their width, and which is the height. I have them lay the object flat on the table in front of them and have the longest side be their length and pointing towards them to get them started.

For the irregular volume, I kept it simple and the kids really liked it.  I placed an assortment of rubber stoppers and marbles on their try.  Some stoppers were solid, some had one hole, some had 2 holes, some were skinny, some were wider. They could place whatever combination they wanted into the graduated cylinder and they recorded what they tried. They also asked questions like “Does the stopper with 2 holes have a smaller volume than a stopper with no holes if they are the same size?” and they tried it out.

They also figured out that if they fill up the graduated cylinder with too many stoppers, they couldn’t find the volume b/c it was more than 100 mL or items were no longer in the water, they were stacked above the water line.

The spoon is there to prevent the items from falling into the beaker, they cover the top of the graduated cylinder, drain the water, and then place the objects back on the try.  Keeps everyone dry!

See below for my notebook pages:

pg. 20 – Volume Lab: Pre-Lab,  Length, Width, & Height

pg. 21 – Practice: Measuring in cm & mm

pg. 22 – Irregular Volume Lab: Pre-Lab,Water Displacement

pg. 23 – Practice: Reading a graduated cylinder, water displacement, volume (page 1)

pg. 24 – Practice Reading a Ruler pg 1

pg. 25 – Practice Using a Ruler cm #1-10, mm #1-10

pg. 26 – Practice using the formula L x W x H  pg.1

pg. 27 – Practice: Reading a graduated cylinder, water displacement, volume (page 2)

Mass, Volume, Density Foldable

Left Side:

Using Publisher, I made a 4 door foldable for the three density related formulas: D= m/v, v= m/D, and m = v x D. The 4th door has instructions on how to solve a word problem. I used the 4 panel brochure template and on the 1st and 4th panels, I made a guide line at 4.25 inches. To make the flaps, simply cut on the dotted lines.

Along with the formulas, inside the foldable are 3 practice problems, and a few notes about mass, volume, and density. I need to make a ppt to go along with the foldable, it will be posted on my notebook page soon.

 

Right Side:

On the right side are practice problems. Students have to determine which formula is needed, set up the problem, and add the correct units. They can refer to their foldable for the formula and how to solve the problems. The problems are not that difficult, my main goal is having them choose the right formula, set up the formula by plugging in the known values, 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 modelling a few problems with them.

Handouts:

• Foldable – legal sized paper 8.5 x 14 (how to shrink to 8.5 x 11)
• Practice Problems
  

Update: Here is the powerpoint I will most likely use as part of our class discussion

Volume: Water Displacement

After we are done with the volume of regular objects lab, we will determine volume using water displacement. This is a lab where setting up the equipment on a lunch tray really comes in handy, its pretty messy! Whenever we use water, I always add a few drops of blue or green food coloring to it. The food coloring makes its easier to read the water levels in the graduated cylinders. Yellow is light, and red tends to stain more than the other colors. I use a large beaker as my stock of colored water then fill smaller beakers with it. A few drops per 100 mL is plenty.

This will be a stations lab with 10 stations. On each tray, there will be a beaker (200 – 250 mL) of colored water, graduated cylinders (10 mL, 25 mL, and 50 mL), two items to measure (rocks, small rubber stoppers, marbles, pennies, etc..) and a plastic spoon. The plastic spoon is a must have for this lab. How so? Lets say the kids are finding the volume of a small rock, they drop the rock into the graduated cylinder, find the volume, now they have to get it out. I show them how to tilt the graduated cylinder to pour the water back into the beaker while using the spoon to cover the opening of the graduated cylinder. Water pours out while the rock is stopped by the spoon. They can easily take the rock and place it back on the lunch tray.

If that doesn’t work, and the rock (or whatever object they are finding the volume for) falls into the beaker, they can use the spoon to fish out the rock from the bottom of the beaker. Otherwise, the kids are putting their whole hand into the beaker to fish out the rock and their hand will displace the water in the beaker = spills. Another reason to use the spoon is that some objects, like metal cylinders or marbles, can crack the beaker when it falls out of the graduated cylinder. (also, to prevent the grad. cylinder from breaking when an object is placed in it, place a small rubber stopper inside the grad. cylinder)

I usually remind the students that when they fill up the graduated cylinders to only fill it about half way with water. This allows room for the object to be placed into the graduated cylinder without the water running over. I also remind them to record the starting volume, drop the object in, record the final volume, and to subtract the final volume from the stating volume to calculate the volume of the object. (1 mL = 1 cubic cm)

Prior to starting the lab, we will talk about Archimedes, how to read a graduated cylinder, what a meniscus is, what displacement is and how to use it to calculate volume, and how to determine the increments to read the volume. We will also do a few practice problems as a pre-lab.

Left Side:

• Pre-Lab- reading a graduated cylinder
• Lab Sheet- water displacement activity

Right Side:

• Practice: Reading a Graduated Cylinder and determining volume by displacement (page 1)

Volume = L x W x H

For this lab, I’ll introduce how to calculate volume for regular objects (rectangular prisms) using length x width x height. (Sciencespot.net has a very good PowerPoint for volume that I may use as an intro prior to this activity.) I’ll demonstrate how to find the 3 dimensions and how to measure to the nearest mm. For the pre-lab, I have a few practice problems to model how to use the formula.

Left Side:

I usually set this lab up as a stations lab. I’ll have 10 stations set up around the room with a variety of objects for the students to measure at each station. Some objects include boxes of: tissues, chalk, crayons, colored pencils, scotch tape, markers, as well as wrapped package of index cards, a dry eraser, a textbook, blocks of wood, etc…

Students will travel with their lab partners and each student will measure one item of their choice at the station they are at (I usually have 2 objects at each station). Students will have a set time at each station and then rotate through 8 of them. When they are done, they can use a calculator to find the volume of each object.

Once everyone has calculated the volume, we go over the answers to make sure their calculations were correct. There is usually an acceptable margin of error for the volumes, depending on how precise they were with their measurements. Students may be +/- a few mm per measurement.

Right Side:

I created a measuring worksheet for cm and mm. Instead of a regular “measure the line and write it down” kind of sheet, I made it a little bit different. The students have to find the line that matches the measurement indicated, and this involves some higher order thinking and processing skills. For example, the first one asks for a line that is 2 cm long. The students look at all the lines and think, “OK, I need something that is small. There are 2 lines that are smaller than all the rest, let me see if one of them is 2 cm long.” They continue this process for all the cm & mm lines.

Handouts:

• This is the pre-lab sheet for the top of the left page.
• This is the lab sheet for the left page.
• This is the measurement practice sheet for the right page.