One of my favorite case studies to examine with students is the tragedy that occurred at Lake Nyos. Located in Camaroon, Africa, Lake Nyos is a lake that formed in a volcanic crater. While villagers thought the volcano was dormant, it was slowly releasing carbon dioxide into the lake. One night in 1986 the carbon dioxide built up enough that the lake overturned and all the carbon dioxide was released into the atmosphere. Since carbon dioxide is more dense than air, thousands of villagers and livestock died in their sleep that night of asphyxiation.

While it is a devastating story to learn about, it is good in the sense that it can be applied to so many science concepts. Biology teachers can bring it up when learning about the carbon cycle. Earth science teachers can discuss the story during their volcanoes unit. Physical science teachers can use it to introduce density of gases. It's a phenomena that is so versatile!

I begin the lesson by showing this video clip from National Geographic on Youtube. It gets the students 100% engaged and doesn't reveal why this mystery fog killed the villagers:

Following the video clip I have students read an article I wrote about what happened at Lake Nyos and the science concepts behind it. You can find the article HERE if you would like to download it (appropriate for grades 7-10).


Then at the end of class I like to end with a demo showing how carbon dioxide is truly more dense than air. All you need are 3 birthday candles, some clay or play-doh, a container, baking soda, and vinegar.
Cut two of the candles shorter so all the candles are different heights. Stick them to the bottom of a container with clay. Sprinkle the bottom of the container with baking soda and light the candles. Have students predict what will happen when you pour some vinegar into the container. Students will observe the lowest candle extinguishing first because the dense CO2 that is being formed stays nearest to the bottom of the container. (I do it under the document camera so all students can watch, but if you trust your students with matches you can have them do it in small lab groups instead). 

I hope your students enjoy this lesson- I know mine do! It's simple, engaging, and a story your students won't forget.

Want a fun way to change up how you assess your students? While there is value in giving multiple choice assessments (students need to have these test taking skills to pass the ACT and SAT), I also like to change it up. Not all students do well with multiple choice or written tests, and offering creative ways for students to show their learning is always fun.

I recently finished my cells unit, and asked students to create an infographic on an organelle. We used the website piktochart.com which is free. (There are paid upgrades, but everything students need is available with the free account). Students found the website to be relatively user friendly- everything is click and drag. 

The project students about 4 class periods to complete. The first day I showed the students sample infographics and we discussed what characteristics were of a good infographic. If you want some samples of quality infographics there are a TON on pinterest. Then I had students do background research on their organelle (I required a minimum of 5 facts on their infographic). The following two class periods students created their infographics and do some peer editing. On day 4 students finalized their edits and submitted them to me. The biggest hiccup we tried to avoid was it turning into a power point slide with a bunch of text. I reminded them that the goal of an infographic is to use images to make complex information quick and easy to understand. For example, if you state that the average US meal travels 1500 miles from farm to plate, how can you help the reader visualize that? (It's roughly the distance from New Orleans to Phoenix, so they could include a map).

Here are some sample infographics we came up with:

Prior to turning in the inforaphics we did a few rounds of peer feedback and editing. This will save you a lot of time later when you go to grade them. After editing students shared the link to their infographics in an email to me, but you could easily have them upload it to google classroom or canvas if you use these tools. Also, if your library can print them poster size they are great for classroom decor!

If you are interested in checking out the forms and grading rubric I used for this project, you can check them out here.
I hope your students have fun creating them!

One of my favorite parts of the cell unit is teaching about membranes. If you ask me, they are by far the most important part of the cell. Everything the cell does is because it is responding to signals received by the membrane. While many students think the nucleus is in charge, it is in fact the membrane that is directing cell processes. (You can read a blog post about why the cell membrane is more of the control center than the nucleus by clicking HERE). 

There are a ton of lab options you can do for students to understand the structure and properties of the cell membrane. Check out these 10 resources you can implement in your classroom: 

MEMBRANE PROPERTIES & STRUCTURE
1. Visualizing the Membrane: Using analogies really helps students visualize the cell membrane in their head. I read this analogy a few years ago in a book by Dr. Bruce Lipton and have been using it ever since. I tell the students the cell membrane is like a bread and butter sandwich. If I poured water on top of the sandwich, what would happen? Students can recognize that the water would only soak through the bread and stop at the butter layer. Since students already learned about lipids being hydrophobic from our macromolecule unit we circle back to that discussion. Click here if you would like to check out a worksheet that goes with this analogy.

2. Bubble Lab: Who doesn't love to play with bubbles?! Bubbles are a fun way to examine properties of membranes because they are similarly made of molecules that have a hydrophobic side and a hydrophilic side. In this lab students learn how membranes are flexible, can self repair, how materials move in and out, and more. Materials are inexpensive and the fun is endless. You can find it FREE HERE.

3. Interactive Website: Check out this website that walks students through the structure of the cell membrane. This website is great for high school students. I like that it shows the actual molecular structure instead of just head and tail blobs... this allows students to really comprehend the structure. While you are there check out some of his other interactives- they are all great!

MEMBRANE TRANSPORT (Many of these labs demonstrate the same concepts. Pick one or two that you like!)

4. Carrot lab: This lab is great for middle school students to understand osmosis. In this activity, students will soak a baby carrot in fresh water and salt water overnight and observe any changes to it's physical appearance and mass. (You can use celery, potatoes, or any other vegetables you have on hand). I prefer using vegetables over gummy bears (Which is a teacher favorite) because vegetables are actually made out of cells.

5. Egg Lab: In this classic lab, students dissolve an egg shell with vinegar and are able to observe a "naked" egg. Once the shell is dissolved you can soak the eggs in different liquids such as distilled water or corn syrup and observe the effects on the egg size and mass. This lab is fun, but I don't do it every year because there are always messy casualties. You can read more specific directions HERE.

6. Dialysis tube lab: In this ADI lab, students need to design an experiment to determine the effect of solute concentration on the rate of osmosis. (Note: ADI labs are available for free online, but the hard copy books must be purchased if you want the answer key). This is a great lab for high school students who are ready to think critically and design their own experiment. Sugar can also be used instead of salt. When I had students complete this experiment I pre-mixed the solute concentrations and we discussed how dialysis tubing works but had students figure out their own experimental set up.

7. Onion Skin Lab: Have you already taught students how to use microscopes? If so, this lab is fool-proof. In this lab, students observe a thin layer of purple onion under the microscope. They make wet mounts with fresh water and salt water, and observe what happens to cells placed in a hypertonic environment. You can read a blog post with some tips HERE. It's great because it's easy (no dye needed) and really inexpensive.

8. Osmosis Tonicity Worksheet: I created this quick 2 page worksheet to use as a formative assessment before I tested students on osmosis. It includes a handful of scenarios and students have to identify how the cells will respond and if the solution is hypertonic, hypotonic, or isotonic. You can download it here.

9. Amoeba sisters: Do you want to enrich your lesson with some videos? Amoeba sisters videos on youtube are great for review and reinforcement. There are two video clips that cover topics relating to the cell membrane, one titled "Inside the cell membrane" and another titled "Cell Transport."
Don't forget that many of the amoeba sisters videos have worksheets to accompany the lesson. They can be found here.

MEMBRANE FUNCTION
10. Cell membrane close reading: One thing students tend to struggle with is understanding how the cell receives and responds to signals. When we use the term "environment" students think about the outdoors... but the environment for a cell is the conditions inside our bodies. I wrote this close reading article to help students understand how the cell receives and responds to signals, and how genes can be turned on and off. It is a great segue into genetics because it introduces the topic of epigenetics.


I hope you have a great cells unit and your students have a blast with some of these labs!

Who doesn't love watching people get pranked? Now add science to the pranks and you have a great way to keep your students engaged. SciJinks is a new show on the Science Channel that uses science to perform practical jokes on people. Following the pranks they explain the science behind it, so it is great for your science classroom. You can see episodes by clicking here.

I made a worksheet to go along with the show if you choose to show it in your class! Click on the PDF below to download. 

I had the pleasure of meeting Tamara Robertson, one of the hosts of the show, at​ a NASA social event (you can read about the NASA launch here). Her resume is impressive- ranging from chemical engineering to TV host. I was able to get her to answer some interview questions, so keep reading to learn more about her!


What is your scientific background and what made you interested in science?
 I am a chemical & biomolecular engineer.  I spent a little under a decade working in facility startup and designs as well as additive technology development for packaging.
I’ve always been good at math and science in school and liked machinery and building things but honestly never thought to pursue science.  I had a teacher in college that took me aside and talked to me about engineering - at the time I thought only boys did that because I had only known one male engineer and that was Scottie from Star Trek.  She helped broaden my view of the world and potential majors and that’s how I ended up in Engineering :)
 
Tell me a little bit about your job history- How did you end up with Mythbusters and Scijinks? Was TV something you always had an interest in?
 Growing up in North Carolina I didn’t have cable as a kid but always enjoyed watching shows and movies on VHS with friends.  
In college I got recruited to do commercial print modeling with a local agency and as someone that really enjoyed sci-fi and fantasy type books the idea of playing make believe sounded fun so I started pursuing acting.  Doing commercials and acting in independent films helped me to overset the cost of living for college so it became a hobby of sorts while I was in school and an engineer. In engineering I was lucky that my degree allowed flexibility in career fields and industries so I got to take some really cool jobs.  Some of the highlights were:

• In college for my undergraduate research I helped run the departments biodiesel plant to make fuel out of different waste materials for the schools farm. 
• My first job out of college was a Greenfield StartUp of the first mammalian cell based flu vaccine facility in the US.  I got to help tech transfer the process from Germany and was even sent to the United Kingdom during the swine flu pandemic to make vaccines for the US.  I later got to work with the CDC and WHO to develop the avian flu seed stock.  It was a really amazing job because I learned a lot very quickly, saw a lot of the world and got to help a lot people.
• I interned with a Plastics Additives company in my my undergraduate program and developed a patent for clarification technology that they still utilize which was pretty neat.  Later in my career I returned to that company to do business development in the packaging industry which led to a lot of cool product design launches with Fortune 500 companies.  For instance, the cups at Starbucks used to be PET but in order to establish a greener portfolio we helped transfer them to a clarified PP which reduced waste in landfills.
• Throughout my career I was taking part in women leadership programs and seeing them be created. There were a lot of women available to join them within the organizations I worked in so in 2015 I decided to transition full time to outreach to try to inspire more diversity and inclusion in STEM.
• Oddly enough about that time they started seeking new Mythbusters so I applied thinking if I could get on the show, even if I didn’t win, I could  help show that women builders can do anything Make builders can do.  I never expected to be the only two MVP winner or Final Female standing but I was very blessed that I was because it’s opened up the ability to talk to so many kids across the nation about STEM and all the opportunities there are within this career path.  
• From there I have continued to have the opportunity to represent women in Engineering as part of the Mythbusters Franchise (Mythbusters The Search, Mythbusters 2.0, Mythbusters Jr) as well as on Scijinks.  When I’m not filming I continue to do relief work across the country, outreach with nonprofits and superhero science with comic conventions.  I continue my job as an engineering consultant as well and get to make a lot of cool stuff!

 
Why do you think SciJinks would be a great addition to the secondary science classroom?
 Scijinks was a really fun program to be a part of because we got to utilize new emerging technology as well as some really cool old school tech to blow people’s minds with science! People often assume that science is just what is done in a lab or from a cubicle but really Science is all around us and there is such a vast number of specialties and career opportunities which I think Scijinks helps to elevate.
We also had a live audience of actual STEM students in the studio with us reviewing our field experiments which helped showcase the diversity and inclusion in these fields.
 
What is your favorite memory from filming the first season? 
 My favorite memory from the first season was probably when we utilized Hydrophobic coatings to create a “stain proof” jacket.  I remember thinking - people are going to know what this is, it’s in so many materials - but in reality no one had ever seen it up close before so they all thought it was this type of magical formula! Getting to showcase to them close up how the technology enables fluids to bead up and repels them from the fabrics was really fun!  Adding that to convincing them to throw an entire vat of spaghetti sauce at our “chef” and things just get hilarious!
 
Do you have a past teacher who was influential in your passion for science?
 I had some really awesome teachers in school- especially in science!  
In high school I still remember one professor Chip Howe. He dropped a piece of sulfuric acid on his shoe but didn’t realize where it had fallen so he continued demonstrating how the compound could burn through materials. About the time the sample on the table was breaking through the piece on his shoe had as well and he had quite a surprise!
 In college at NC state I honestly had some of the most inspiring professors! Dr. Bullard was instrumental in keeping me driven and pushing through all the hard moments in school as well as graduating and trying to get work during a recession.  Since she had been an engineer in life before teaching she was an amazing resource with regards to navigating the job market, building a portfolio and experience based resume while in college and was an amazing example of someone who had a career in STEM and a family and made it work.   
 
What advice would you give to teen girls interested in STEM careers? 
 There’s so many pieces of advice I would give here - here are a few of many:

• Know that where your journey starts doesn’t define where it ends, you do.  As long as you work hard and never give up you will eventually achieve your goal and no one can take that away from you.
  
• Never see yourself as a girl in STEM but instead see yourself as a human in STEM.  If you believe in your skills and put in the time to gain the knowledge and experience you need to succeed you will succeed.  
• Hold your own and believe in yourself - especially if you’re the only person like you in the room!  When I went into the world there was no example like me for me to look at as a role model, so instead I found role models that had traits I wanted to build and I set out to learn from them. Always have a mentor, even if they’re an indirect one that you’re just observing them to learn - as a science observation is key to advancement.  
• Invest in your education.  It will be hard work, a lot of hard work but if you buckle down and take it seriously you will be able to enjoy the rest of your life with less stress and worry.  Homework is exhausting but it is necessary to gain knowledge and skills and the long hard hours in school will eventually mean relaxing evenings at home.
• Just ask.  The worst anyone can say is no but if you don’t take the risk and ask you’ll never know.

 
If people want to find you on social media, where can they look?
 I can be found on all social media platforms under the handle @tlynnr85.

Guest speakers can be such a powerful tool to your classroom and are hugely underutilized. I don't think I truly understood their value until I started teaching project based learning. Part of PBL includes having a public audience (you can check out a blog post on this topic here). As I developed projects and started bringing in people from the community it made a huge impact on my students.

Why are they so powerful? First, students are used to hearing us teach every day, and don't always give us 100% of their attention (who am I kidding, they RARELY give us 100% of their attention). But whenever I've had a guest speaker come in, the students seem to hang on to their every word. Another reason they are invaluable is because they can bring in a level of specialized content knowledge that you don't have.

For example, I recently had my students complete a project where they had to design a food truck. We had been learning about sustainable agriculture, macromolecules, and nutrition. Students were asking questions I didn't have specific answers for, like how much local ingredients would cost and how they could decrease their company's carbon footprint. I could have done some internet research to help them find the answers, but why not go straight to the source? I sent a quick email to the owner of a farm not too far from our school asking if students could ask her some questions over the phone about her business. She was more than happy to speak to them and talk about her organic farm and the struggles of starting a small business. They were able to record the phone conversation and refer back to it later as they prepared for their presentations.

Where to find guest speakers
I promise when you begin to reach out to people in the community, you will be surprised how willing they are to come in and speak to your students. You won't always get a yes, and you won't always find people that can stay all day and speak to multiple class periods. (One way to solve the multiple class periods issue is to record the presentation and show it to your other classes). I've had luck tracking down people willing to speak to my students from almost all of the places listed below:

• Utility companies- energy companies, water, or waste
• Local business owners- endless opportunities here
• School resource officer or local police
• Spouses of colleagues- shoot a quick email to your staff asking if anyone has a connection with the topic you are teaching.
• Game and fish department or zoo employee
  
• Parents of students
• Professors from your local university
• Blood services employee
• Local news or radio station
  
• Former students who are now in college
  
• Nonprofit organizations- They will almost always come, especially if you are organizing some sort of fundraiser to support them

Don't forget to check out company websites! As I was recently teaching about genetics and GMO's, we were discussing golden rice and how food can be genetically modified to increase the nutrition for malnourished people. I looked up a website for an organization in my city called "Feed My Starving Children" that packages and ships food to third world countries. And guess what- they had a link that said "request a speaker." Bingo!

The Beauty of Modern Technology
While it is always ideal to have someone come in and meet with your students personally, this isn't always possible. But there are other options! Websites such as www.skypeascientist.com allow you to do a skype or google hangout session with a scientist. You choose which type of scientist you would like to skype with based on what you are teaching and they will match you up accordingly.

I've also had students do phone interviews with multiple people ranging from professors at our local university to food truck owners. If you email people and ask if they have 10 minutes to spare for a quick phone conversation they will almost always say yes. As a bonus, it is good practice for students to learn how to speak professionally on the phone.

A closing tip....
Most guest speakers that come in aren't used to speaking to teens. They do a great job, but don't have the same practice you do. One thing I've noticed is that they aren't used to what us teachers call "wait time." They tend to ask a question to students, wait about 2 seconds, and then answer it if they don't see hands go up.
When the guest speaker comes, pull them aside quickly and give them a gentle tip to wait a while after asking students a question. Explain to them that students need much longer processing time than adults. I've never had anyone be offended by me giving them this tip, and it's made the classroom discussions much better.

Good luck finding a guest speaker and enjoying a day of listening and learning instead of teaching!

Getting out the microscopes is one of the best parts of teaching biology. I love hearing the ooh's and aah's when they finally get the specimen into focus. But if you've taught biology before you know it can also be one of the most exhausting units- constantly running around the room because "Mrs, I just don't see anything!" or they end up drawing dust, air bubbles, or their eyelashes. After a decade of tweaking my microscope unit, I've come up with some tips to help save your sanity. 

1. Don't get them out until it makes sense.
While it may be tempting to get microscopes out the first week of school, it just doesn't make sense. If you aren't going to use them regularly until later in the year, why are you teaching them the names of the microscope parts in week 1? They will forget the information and you will find yourself reteaching. Hold off until you get to cells (or whichever unit you need them regularly).

2. Make sure they know the names of all the microscope parts. 
It can be really frustrating when you are trying to help a student, tell them to adjust the fine focus, and they look at you like you are speaking another language. Because of this I don't let students start using the microscope until they can tell me the names of all the parts. We take notes on it and I give them a short quiz at the beginning of the unit. If you want to check out the worksheets I use for teaching parts of the microscope, click here.

3. Try a virtual lab first
Virtual labs are a way to provide students extra practice on the methods of using a microscope before getting out the real deal. Extra practice never hurts, especially for your SPED or ELL students who would really benefit from some visual practice.
For practice going through the process of using a microscope, check out this activity from Brainpop. (This site is great for middle school). For some higher level practice, check out this site from University of Delaware.

4. If your scopes have a single ocular, teach them which eye to use.
The microscopes in my room have a single ocular lens, so students often ask me which eye to use. This video shows an easy and quick way to teach them which of their eyes is dominant.

5. Start with prepared slides.
I always begin with prepared slides. I put 4 different prepared slides at each lab group, and have students practice focusing and drawing. The first day of prepared slides you will hear a lot of "I don't see anything!" but eventually they get the hang of it. Not all of your students are going to be great artists, but I make sure they know when they turn in their drawings they must a) be drawn to scale, and b) be neat. No scribbles allowed. I should be able to look at the drawing and easily tell what slide it is. I use these lab templates for prepared slides. Don't have access to prepared slides? You can make your own! Check out this blog post on how to easily make a classroom set.

6. Encourage peer help
There is only 1 of you and 30 students. It is physically impossible for you to be running around helping every single student. One day when I was about to rip my hair out I made this poster and hung it up on the whiteboard. Students were not able to call me over for help unless they had checked all of these items off the list. Most of the time their neighbor can help them resolve the issue before you need to be called over. If they still needed help after going down the checklist, then they could call me over. It has helped greatly! You can download this for free in my TpT store here.

7. After they have mastered prepared slides, then move on to wet mounts
Wet mounts can be much more exciting than prepared slides because you can have students look at their own cells (if your school allows you to do a cheek cell swab) or watch microorganisms swimming around. Protists are an absolute blast to watch, but students need to have mastered focusing the microscope and scanning relatively quickly in order to see the protozoa zooming around. You don't have to spend money ordering protists from a supply company, you can easily get your own culture going. Check out this blog post on how to set up a hay infusion. During this lab, I allow students to take pictures or videos with their phones. It takes a steady hand, but they can line up their smart phones with the ocular and get a decent video.

8. Clean-up
It can be really frustrating when the bell is about to ring and students try to walk out of the classroom without cleaning up. General microscope clean up procedures should include:
a) Removing your slide and returning it to where the teacher directs
b) Turn the objective to low power
c) Turning off the light
d) Putting the dust cover back on
e) If you are putting microscopes away for the day, unplugging and winding the cord around the arm.

I have this poster hanging on my microscope cabinet- it is a freebie from my friend Bethany Lau. You can find it in her TpT store.

I hope these tips help your microscope unit run more smoothly! Have fun!

Why are cells so small? And why are we made of so many? It seems like it would be easier to be made of 100 or even 1,000 cells instead of trillions. One of the reasons we teach students that cells are small is because they need a large surface area to volume ratio. The larger the ratio, the more efficient the cell is at moving materials in and out of the cell.

I've seen cell size labs that use different sized agar cubes prepared with a pH indicator. The cubes start pink and lose their color as they soak. Frankly with 3 preps a day this year, I didn't have the time or energy to pour agar cubes. Instead I found a quick and easy way for students to see the same concept- using beets and bleach.

In this experiment, cut different sized beet cubes, a small, a medium, and a large. The students soak the cubes in bleach for roughly 30 minutes (I had them doing some practice SA:V calculations while they waited). Tip: if you use tupperware containers with lids you won't have to smell bleach fumes all day, or you can put parafilm over the beakers.

After 30 minutes of soaking, students remove the beets, cut them open, and measure the amount of red pigment remaining. It is an easy way to see that small cells are more efficient at moving materials in and out. If you are interested in seeing the lab write-up I wrote, you can view it here.
I hope your students enjoy it!

Movies is often much more engaging than lecturing to your students. Having students actually see extinction happening in the documentary Racing Extinction is much more powerful than me talking about it. While I don't usually show full length movies in my classroom (more often clips), they can be a great supplement to your curriculum. I've compiled a list of movies that could be added to your science classroom curriculum. Tip: If you require students to answer questions during the video or have a follow up assignment, you will have more students paying attention!

Disclaimer: I have not personally seen all of these movies, and always suggest previewing before showing and making sure it is appropriate for your grade level. Depending on the movie content and rating you may need admin/parent approval.

Have any suggestions to add? Drop them in the comments!

If you teach BIOLOGY
This idea is for my fellow biology teacher friends! It seems like every year the day after Halloween all you do is hear rustling of candy wrappers begin opened during class. It's a battle I've stopped trying to fight. Instead of saying "put away the candy," tell them to get it out! Have students pull out their candy, lay it on their desks, and classify it and make a cladogram. You will have some students that don't bring in candy, so I bring in my leftover candy from home. It's a win-win: students get to learn while eating candy, and I don't eat all the leftovers and save myself some time at the gym!  

If you teach CHEMISTRY
One of the best parts of teaching chemistry is getting to play with dry ice! In this lab activity, students explore phase changes and sublimation while comparing the change in mass of dry ice in water vs. regular ice in water. I have students use triple beam balances instead of electronic scales because it is good practice for them to adjust the hanging masses and practice their measurement skills. 

If you teach FORENSICS
Analyzing blood spatter is always an easy way to keep students engaged! Check out this quick and easy lab from the science spot where students learn about blood spatter patterns.

Lastly, if you just want to re-enforce some scientific method skills (observation and inference, CER, and graphing), check out these fun Halloween themed worksheets! 

I hope you have a Spook-tacular Science Halloween!

Air pollution is a topic that fits into almost all science content areas. Teach biology? You teach the water and carbon cycles. Environmental science? Climate change and smog. Earth and space science? Layers of the atmosphere and ozone. Chemistry? Water + CO2 = carbonic acid. (Side note: My students recently tested the pH of different water sources, and were blown away that the pH of our rainwater sample was 5.4). I think it is telling that our air and atmosphere are woven into so many different sciences. Air is vital, so let's talk about it with our students! 

I recently did a mini unit with my students on urban ecology. We were learning about the effects of urbanization on ecosystems, and pollution and urban heat islands came up in our discussions. (You can read my blog post about urban heat islands here). Here in Phoenix it is relatively easy to see how polluted our air is, all you have to do is drive up a hill and you will see the layer of haze that sits over our city of 1.6 million people. We discussed the health effects of air pollution and I wanted my students to have a visual of what they were breathing in. You can buy fancy (and expensive) sensors that will give you data readings of all the particles in the air, but I found an easy way for students to see the particulate matter floating around. 
​
You will need:

• Glass slides (gridded slides are ideal) 
• Cover slips
• Compound microscopes
• Petroleum jelly or double sided tape
• Cotton swabs
• Optional lab write up can be found here

This lab is super easy. All you have to do is have students smear a thin layer of petroleum jelly across the center of a glass microscope slide with a clean cotton swab. If you want your students to have quantitative data at the end of the experiment, gridded slides are ideal (See image). No worries if you only have plain slides. 

Students got to choose where they wanted to leave their vasaline-covered slide for 24 hours. I had some students leave the slides in the classroom and others left their slides outside. (Tip: I had students set them in a petri dish and label them with their initials so we could track them down easier the next day. Also, if students choose to leave them outside, find a location on your school campus where they won't get disturbed). In the next 24 hours, any particulate matter floating around will land on the slide and stick to the petroleum jelly. If you want easier cleanup, you can also try putting a piece of double sided tape on the slide instead. 

The next day, students retrieved their slides and viewed them under the microscope. I had them switch slides with their neighbors so they could compare indoor vs. outdoor slides. As you can see from our results pictured below, there was generally a lot more particulate matter on the outdoor slides. I had students draw what they observed and do a little math to calculate the particle deposition rate. If you are interested in checking out the lab write up, click here. 

Remember when I said there was generally more particulate matter outside than inside? Are you ready to be completely grossed out? I had a student that decided to hang his slide from the ceiling by the classroom air vent... and this is the image that ensued. Can you say "time to change the air filter?" 

I hope your students enjoy this lab as much as mine did! It was definitely eye opening for them to see the microscopic matter going into their lungs. 
​Enjoy!