How Thick is Aluminum Foil?

Measurements, Significant Figures, and Density

The first unit in chemistry class includes measurements and general number sense. There are several labs that we do and review as a class to get the idea of significant figures.  One of these labs involves determining the thickness of aluminum foil. First the students had a warm-up as the bell-ringer:

Class Warm-up:  Density

 Remember the relationships:
 Density = mass/Volume and  Volume = length x width x height.

These two equations can be combined to yield:
D = -----------------------------
                l x w x h
If you wanted to know how “tall” something is, you would solve for h, as in the equation following:

 h = -----------------------------
                D x l  x w

Solve the following problems:1.       What is the volume of a block that is 8.20 cm long, 2.25 cm wide, and 1.00 cm high?
2.       If the density of a substance is 0.525 g/cm3, and the volume of a sample is 18.25 cm3, what is the mass of the sample?
3.       A piece of paper is known to have an area of 595.5 cm2 and a mass of 4.589 g. What is the thickness (height) of this paper, if paper has a density of 0.72 g/cm3?

Class Activity: Foiled

Pre-cut squares of three types of aluminum foil were set out, and students were directed to take the measurements needed to calculate the thickness, based on the warm-up calculation above. The density of aluminum was given to the students as 2.70 g/cm3. I tried to cut the squares so that they were not an exact centimeter size, so that students would need to read the mm lines and estimate a "between the lines" digit.
Foil squares origami envelope
Pre-cut squares of foil saves time.
I made quick origami envelopes to store them in. 

foldable origami envelope
Origami pocket directions

Physical versus Chemical: How do you know?

We are in the first two weeks of chemistry and everything is about "How science is done?": the maths, measurements, observations, evidence, data recording, you know the stuff.  One of the labs was a nine-station physical versus chemical lab. When they were finished with the experiments I had the students go back to tables that did not include their lab partners and consult with others on their conclusions. They shared observations and were directed to argue with each other on whether a particular station was a chemical change or physical change. I felt this piece of the work was important for students to understand that their analysis and conclusion must be defendable with evidence. We also used this time to talk about when scientists disagree. Last year I incorporated POGIL into my lessons. This year I am adding ideas about teaching and learning through argumentation; argumentation is really evidence-based reasoning in relation to scientific and social issues.

A couple of side notes:
  • A variety of waste disposal methods are asked for, depending on the station, which was good practice for the students. 
  • Nine stations may be too many for some classes. I found it perfect for many, but one too many for some.
After the lab, the class shared results as a whole and came up with definitions for physical change, evidence of physical change, chemical change, and evidence of chemical change.  These definitions were added to the students' interactive notebooks in the form of the following foldable. 

Finally, for the assessment, students were asked to write a well-developed conclusion (at least 4 sentences) about what was learned and what types of observations (evidences) can be used to tell whether a physical or chemical change has occurred.

For those that are interested, the entire lab assignment follows.

Physical vs. Chemical Change Lab

Background Information

How can you describe a pile of gold scientifically? You talk about its physical and chemical properties.  Physical properties are characteristics that can be observed or measured without changing the makeup of the substance. Examples of physical properties are each phase of matter, color, density, weight, volume, texture, taste and smell. Chemical properties are characteristics that identify the chemical makeup; examples are elements from the periodic table.

What happens if I want to melt my pile of gold to make coins? This would result in a physical change.  These physical and chemical properties can change. Physical change defines when a substance has changed its “look”, but not its chemical substance. Examples of physical changes are melting, freezing, cutting, boiling or mending. A chemical change forms new substances; material goes through a chemical reaction. Examples of chemical reactions are rusting, creation of gases or bubbles, burning wood, cooking.


Write a description of the differences between physical and chemical reactions. What are properties and changes? What are examples of physical properties, physical changes, chemical properties and chemical changes?


Set up a data table in your journal that allows for identification of the station, recording of observations, and whether it was a physical or chemical change. 
Example data table:
Station # and name
Physical or chemical change?

Station 1
·         Add a small scoopful of sodium chloride into a half-full 100 mL beaker of water. Stir the contents of the beaker for approximately one minute.
·         Record your observations.
·         Pour the solution down the sink and rinse out the beaker when you are finished.
Station 2
·         Pick up a small piece of magnesium ribbon with the crucible tongs and heat it over the Bunsen burner until you observe a change.
Station 3
·         Pick up a small piece of zinc with crucible tongs and heat it over the Bunsen burner until you observe a change.
·         When you have finished, place the residue into the beaker of water provided.
Station 4
·         Fill a test tube halfway with silver nitrate solution.
·         Quickly squirt an entire pipette full of sodium chloride solution into the test tube.
·         Record observations.
·         When you are finished at this station, pour the contents of the test tube into the waste jar provided, fill the test tube with water (for rinsing) and pour that water into the waste jar.
Station 5
·         Pour 25 mL of acetone into the glass dish.
·         Place a piece of Styrofoam in the acetone.
·         After making observations, remove the Styrofoam with a glass stirring rod. Pour the acetone into the used acetone beaker provided.
Station 6
·         Cut a SMALL fresh slice from the potato.
·         Use a dropper to put 3-4 drops of iodine solution on the potato slice. Record observations.
·         After your observations are complete, throw away the used slice of potato into the trash can.
Station 7
·         Strike a match and watch it as it burns. Blow the match out before it burns your fingers.
·         Dispose in the used matches can.
Station 8
·         Pour about 1 cm of hydrochloric acid into a test tube.
·         Place a small chip of marble in the same test tube.  Make sure the acid covers the chip.
·         Record observations.
·         When you are finished making observations, pour the test tube contents into the waste HCl beaker provided and rinse out the test tube.
Station 9
·         Take full dropper of the acetic acid (vinegar) solution and squirt its contents into a 50 ml beaker.
·         Using the ammonia dropper bottle, add ammonia drop-wise into the 50 ml beaker.
·         When your observations are completed, pour the contents down the drain and clean the beaker with water.

Data Analysis

Answer the following questions in your journal:
1. List all of the chemical changes you observed.
2. List all of the physical changes you observed.
3. What were some of the observations that indicated a physical change had occurred?
4. What were some of the observations that indicated a chemical reaction had occurred?


Write a well-developed conclusion (at least 4 sentences) about what was learned and what types of observations (evidences) can be used to tell whether a physical or chemical change has occurred.

Modifications Teachers Do

This past semester I had an extremely small class of bright but shy students. No matter how much "wait time" I gave or how carefully I phrased discussion questions, dead silence followed. I'm not one to run a monologue so I had to do something. I started handing out 3x5 file cards when I wanted to get some dialogue. Students would write their thoughts down, I'd collect them and leave another for the next question. Then I would share responses and phrase a follow up based on what I read. It is not a perfect system but it got us going through the first half of the semester until the students became comfortable enough with each other to speak out loud.

Critics will say that I did not help them become more independent but I did what I could for pushing thinking about the subject matter (I did force a couple research presentations). Short thoughts I would write on the smartboard so we could organize ideas and expand on them.
I post this in the interest of saying: 
Dear government administrators, teachers naturally modify lessons every day based on individuals, individual classes, class dynamics, and current events. We don't have to write out every modification we do and document it on a form - none of us have time to do that for every situation we modify!- we do it naturally. Teachers are professionals, so please give us that respect.

(Readers please note that I am speaking to all those that would add "accountability" in the form of documentation and not to my personal administration.)

From Tap To Toilet: Interruptions in the Water Cycle

Students learn about the water cycle starting in early elementary grades. They learn how Earth's water is changes forms, between liquid (rain), solid (ice), and gas (vapor), and how it moves from the atmosphere to Earth’s natural systems. But one thing is usually left out: human interruptions in this process.  Even this marvelous interactive map from the USGS misses one big interrupter: humans pulling water from surface waters or groundwaters, using it, and discharging it through septic systems or wastewater treatment plants.

Drinking Water, Wastewater, and Humans

The environmental science class took a field trip to a water treatment plant and a wastewater treatment plant to see for themselves what makes it ok for them to take a drink of tap water and to flush a toilet. As a result of this field trip, class labs, textbook readings, class discussions, etc. students were asked to write an entry describing human interruptions to the water cycle. Items students were asked to include were:
  • ·         Water withdrawal and how it can diminish the groundwater table or dry up a stream, river or lake
  • ·         How humans contaminate water and how humans can prevent some contamination
  • ·         What must be done to clean up water that is flushed down toilets 

Amesbury Water Treatment Facility
Floccing Agent
Monitoring Equipment
Disinfectant Tank

Getting the Tou

Separation Tanks (one empty)

Sludge being skimmed off

Sludge skimming (note white bubbles at far end)

Samples of the Stages

Where our drinking water comes from

Amesbury Drinking Water Source

Settling Lagoon

Thanks for the tour!

Down at the other end of the line is the water that we have used and now needs treating before discharge to the river.

Amesbury Wastewater Treatment Facility

The aeration tank, after the grit is removed.

Happy bugs doing their job.

Settling tank

Taking the tour

Grit removed
Looking at the good bugs.

Lab check for suspended solids

Inside the plant 

Gas Laws Analysis

Assignment for Chemistry Students:

Make your learning a conversation with others!  You have watched demonstrations, read txt, practiced gas law equations, and done some labs, all in the name of understanding how pressure, temperature, and volume were related in a gas.   Now you must take all this learning and write an analysis, a conversation of what you learned. This analysis must be posted on your chemistry blog. 

Write your analysis as a discussion or a story. Please do NOT write your analysis as a list of answered questions, even though you have been given a list of questions.  You will be assessed on 1) knowledge of the subject material; 2) describing the material in your own words and in an interesting manner; and 3) personal contribution to the topic.

Labs you have done related to the gas laws are:

Hot Balloon:  An Erlenmyer flask with approximately 50 mL of water in it and a balloon secured on top is heated, and the circumference of the balloon is measured before and after heating the water.

Cartesian Diver: A 2-liter soda bottle is filled with water and a medicine dropper placed inside. After being capped, the bottle is squeezed.

Soda Can Crush:  A soda can with a small amount of water in the bottom was heated on a hot plate, and then flipped with tongs into ice water.

Pressurized Balloon:  A 2-liter soda bottle that has a balloon inside was pressurized.

Pressure and a Bag:  Two large jars with plastic bags taped over the mouths, one inside and the other outside.

Demonstrations you have seen related to the gas laws include the bell jar vacuum; individually, the following were exposed to a vacuum under the bell jar:  glass of water, balloon, marshmallow, shaving cream, empty water bottle.  You also saw the press of air against an evacuated metal sphere with handles.

Need help with definitions?  WyzAnt has a decent tutorial here.

Snow Days

How Should We Make Up Lost Time On Learning?

The headline reads: Boston in midst of snowiest 30 days on record!

Schools in eastern Massachusetts have experienced an inordinate number of snow days-- ten in my school by mid-February-- and students have been losing valuable learning time. Students not only lose time but they lose the momentum of learning; interruptions in schedule means that the instructor must review and repeat before continuing with the lesson.
If schools take the traditional route of tacking days onto the end of the school year, children will be in school until the last day of June. For some this may not be a problem, but there are many reasons for not taking this standard approach.
  • High school seniors have a graduation date that allows them to get out earlier and do not make up missed days, thus they lose those education hours. Ten snow days results in a 27% loss of learning time for seniors taking a semester course.
  • Other high-schoolers “check out” and lose focus during June and after the seniors graduate. One student phrases this as "At my school, we stop learning new material for the most part around midway through May", and while I disagree about his statement it has been my experience that the students lose focus at the end of May.
  • Many families have pre-set plans for their summer and will take their children out of school to keep their schedule.
  • There are many scheduled exams that students must take and lost snow day hours are added AFTER the exam date will not help them at all. AP exams are the first two weeks in May.  The ELA MCAS exam is March 25th and 26th, the math MCAS is May 12th and 13th, and the science MCAS exam is June 2nd, all of which a student must pass to obtain a high school diploma.
  • Teachers must take summer courses to maintain their certifications and many courses begin at the end of June.
  • Many teachers work a summer job to help support the family.
21st Century education moves beyond standard practices and asks students to be creative, innovative, collaborative, and think outside the box. We should too. Instead of tacking school days onto the end of the year, which will not help students with their state and national exams, or asking students to make up the days on Saturdays or April vacation, which would result in a very low attendance particularly at the high school level, schools should incorporate creative and flexible methods for retrieving the learning time for students. Here are some off-the-top-of-the-head ideas and I'm sure there are many others:
  • ELearning! Children are already consuming information through their smartphones, iPads, and laptops, let's take advantage of that. Online supplemental work could be either independent and on the student’s schedule or it could be scheduled with the teacher present on the other end. Seat time is recorded by the log-in and actions of the student. The examples are endless.  Delphi school in Indiana requires students to log on during snow days. Farmington district in Minnesota uses their "Schoolology" digital platform, and Pentucket Regional School District could use their "Schoolloop" digital platform.
  • Relevant work packets sent home with students that they can do on their own schedule and will count as a given set of hours when turned in. Other states, like New Hampshire, Minnesota, and Ohio have "blizzard bags", which Burlington and Wayland schools have taken up.  This link goes to Contoocook Valley regional schools as an example of one way a blizzard bag could work.
  • Extend the school day one day per week by two hours, adding time to all subjects.
  • Move teacher professional development out of the student’s education time to Saturdays or the end of the year.
Teachers, administrators, and unions need to work cooperatively together to make this school year meaningful and authentic. To get to the job of educating children, let'st stop making excuses for why something CAN'T be done and look at how it CAN be done.

Investigating Ice Cores

Students in environmental science are studying atmosphere and climate change, under the overarching question of What key functions does the atmosphere serve that enables life to exist on the planet?  To gain perspective on this issue students have read the text and watched the "atmosphere", "air pollution" and "climate change" videos on the Habitable Planet, and have brought in current event articles on the Clean Air Act for discussion.  Lectures on the atmosphere, climate, and air regulations have also been presented.

Today students were given "ice cores" to analyze for evidence of air pollution, and to think about the question What can be learned by looking at an ice core?  Student instructions were to 
1.       Identify layers of ice and measure and diagram the layers.
2.       Separate the layers by cutting or breaking the ice.
3.       Measure the mass of the sample. Record results.
4.       Melt each of the layers and measure the pH.
5.       Measure the volume of the sample using a graduated cylinder.
6.       Calculate density.
7.       Carefully extract the ash or boil away the melted ice water and mass the ash.
8.       Report your results on the board.
9.       Compare your predictions to the results of other students.
10.   Look for trends in the data, high and low pH vs. presence of air pollution
11.   Compare your data to the overall class data.

The preparation for this activity required advanced planning.