Earth's oceans are a carbon sink, which is a place where carbon is stored long term. Oceans absorb carbon dioxide from the atmosphere. It reacts with seawater, creating carbonic acid, which in turn lowers the pH of the ocean. This phenomena is known as ocean acidification. It will only get worse as we release more carbon dioxide into the atmosphere. Oceans currently have a pH of around 8.1, but it is projected to lower to 7.7 by the year 2100.
What is the impact of ocean acidification on marine life?
Research is still being conducted on this, but there are a few things we know for sure. First, organisms that rely on carbonate to build their shells and exoskeletons will have less available. These organisms include coral, mollusks, sea urchins, starfish, and zooplankton to name a few. If they struggle to build shells, they are more likely to be eaten by predators and it can create a trophic cascade up the food chain. Other impacts could include lowering the blood pH of fish, changes in reproductive ability of marine life, and impeding with organisms ability to send chemical signals.
Ocean Acidification Lab
An easy way to show students the impact of ocean acidification on marine life is by soaking seashells in ocean water with various pH levels.
For this lab you will need (per group): 3 cups or beakers, 3 seashells, water, salt, vinegar, an electronic scale, and pH paper. Seashells can be purchased at craft stores, and I've even found them at the dollar store in the craft aisle.
Start by mixing up simulated ocean water (3.5% saltwater solution). Students will put ocean water in the first beaker, 75mL of ocean water and 25mL of vinegar in the second beaker, and 50mL ocean water and 50mL of vinegar in the third beaker. Next, have students take the mass of the seashells over the course of 3 days and calculate the percent change in mass. They will see the vinegar eat away at the seashell and a large reduction in mass. You can also have them measure the pH of the liquids over 3 days and see how it changes as carbonate is released (enter discussion on buffers!)
Following the activity you can discuss ways students can lower their carbon footprint so we can slow the rate of acidification in the future. If you are interested in a powerpoint lesson on ocean acidification and a lab write up for this activity, you can find it HERE.
The law of conservation of mass states that mass in a closed system will not change before and after a chemical reaction. Mass isn't created or destroyed, it just moves places. Seems simple enough, but this law can be difficult to demonstrate. It seems nearly impossible to get PERFECT data every time. And when the measurements are off by two hundredths of a gram, students are often yelling "Ah-Ha! Lavoisier was wrong!" (Sigh.....) BUT, it can lead to good discussions on where any change in mass could have come from.
Here are some labs you can use for different grade levels to teach the law of conservation of mass.
Grades 5-6: GLOW STICKS
In this experiment students compare the mass of a glow stick before and after it has been cracked and activated. You should get relatively good data for this lab, but as you can see in the picture the mass decreased by a hundredth of a gram. Glow sticks can be found on amazon, at the dollar store, or you can stock up on them after Halloween when they go on clearance.
Grades 7-8: ALKA SELTZER BAG
In this experiment, students compare the mass of water and alka seltzer in a Ziploc bag before and after it reacts. I'll admit this is a tough one to get great data because the bag is porous and some gas will escape during the reaction. However, it's best to use a bag instead of a sealed container because with a sealed container the lid can pop off from the pressure. I've found thicker name brand bags work better than store brand, so don't skimp to save a few bucks.
One thing you can do after the alka seltzer and water reacts is to let students open the bag, release the gas, and re-weigh (see the last picture on the right). They will see a decrease in mass and learn that gases (in this case, carbon dioxide) have mass. If you'd like to check out the lab worksheet, click here.
Grades 9+: STEEL WOOL
In part 1 of this experiment, students compare the mass of steel wool before and after pulling it apart. Since it is only a shape change and not a chemical change, it's relatively easy to get perfect data as long as they pull it apart over the scale (small fragments will fall off).
In part 2, students burn steel wool and compare the burned mass to the initial mass. (Bunsen burners will give you better data than using matches or candles). What is interesting about this experiment is that the steel wool actually GAINS mass after burning. This is because as it burns it combines with oxygen in the air to form iron oxide. The addition of the oxygen atoms causes an increase in mass. It's a great experiment to get students thinking about chemical reactions and where this additional mass could have come from. If you'd like to check out the lab worksheet, click here.
Do you have any other ways you demonstrate the law of conservation of mass with students? Leave me a comment!
It doesn't matter what age you are, glow in the dark experiments are a blast!
Did you know that tonic water glows under a black light? It has a chemical in it called "quinine" that causes it to glow. You can substitute out tonic water for regular tap water in some of your go-to experiments to make them glow! Here are a few of my favorites:
Ooblek is super fun to make when learning states of matter. Is it a solid? Is it a liquid? (It's a colloid). To make ooblek, you normally mix 1 part water to 2 parts cornstarch. Sub out tap water for tonic water and now you have a glowing non-Newtonian fluid. Around Halloween we call them "ghost guts!"
When teaching cell membranes, many teachers do the classic rubber egg experiment. In this lab, you begin by dissolving the shell of an egg with vinegar (change out the vinegar on day 2 and continue to let it sit about 2 more days). Once your shell is dissolved you are left with the membrane of the egg sans shell. You can take it a step further and soak your rubberized egg in different liquids such as corn syrup and see what happens. This simulates osmosis and how cells swell in hypotonic solutions and shrink in hypertonic solutions.
To make your rubber egg glow, use a 50-50 mixture of vinegar and tonic water. (You could even be sneaky and add tonic water to a random few beakers from the class and freak them out by telling them they must have gotten radioactive eggs).
DIY LAVA LAMP
Want to make your own lava lamp? Fill a container with 50% tonic water and 50% vegetable oil. Turn off the lights, add your black light, drop in an alka selzer tablet, and enjoy the show! This can be done to reinforce density (layers) and chemical reactions (CO2 bubbles).
Looking for more spook-tacular Halloween science ideas? Check out this blog post!
Writing out CLEAR and DESCRIPTIVE scientific procedures is hard for students. It takes practice! Many teachers start off with a fun activity like how to make a peanut butter and jelly sandwich. Students will likely forget some important steps! This Youtube version made me smile:
Anywho, it's important for students to be given opportunities to practice writing experimental procedures and not just be given what we call "cookbook labs" where everything is provided for them.
Here are some ways you can practice:
1. I created a set of 20 unique writing prompts that provide students experimental questions. I like that they not only get to practice writing procedures, but also get critical thinking practice- HOW could they test and set up an experiment to answer the question? It can be helpful to work through an example as a class and then set them loose.
(If you are interested in other writing prompt sets, check out this post).
2. I came across this cool flextangle template and immediately thought "Students will love this! But how do I connect it to my curriculum?"
I think it would be fun to put students in pairs, and chop the paper in half- give one student the foldable template and the other student the directions. Have the student with the directions explain how to cut and fold the flextangle and see if they can do it successfully. After a while, you can show them the video of how the flextangle should work and see how they did. While students won't actually be writing procedures, they will be explaining procedures, which is still great practice.
3. Have a favorite demo you love? Sneak in some writing practice! Show students the demo and tell them to watch what you do very carefully. After the demo, have them write out what you did step by step. You can do the demo a second time if they need to see it again to catch all the steps. After the demo, have a few students read their procedures out loud and see how well they did.
4. In this free activity from Amy Brown Science, students build a unique structure and write out the procedures on how they built it. Then they swap instructions with another student and see if they can replicate the structure.
What other ways do you have students practice writing procedures? Leave me a comment!
Want a new way to review the scientific method and variables at the beginning of the school year? Try having students conduct a consumer science experiment! In this lab students will chose two products that they use in their everyday life and design an experiment to test it's effectiveness.
What's great about this experiment is:
Possible experiments could include:
Prior to "setting students loose" with the task, I would remind them to only choose ONE variable, and review what a controlled experiment is. For example, if they choose to test paper towel absorbency, they need to make sure the two paper towels are the same size. Also discuss the need for multiple trials to get accurate data.
You have a few options for students to submit their work:
Inevitably you will have students that changed more than one variable, didn't have a control, made measuring errors, etc. You can always give them feedback and request the repeat the experiment with needed improvements. This is a great learning opportunity for them, and they will understand that the nature of science is to always go back to the drawing board and improve on prior experiments.
Have any other consumer science labs you love to do with students? Leave them in the comments and I'll add them to the list!
WHAT IS CITIZEN SCIENCE?
Citizen science is when the public participates in scientific research. Every-day citizens share and contribute data with the goal of increasing scientific knowledge. You do not have to be a trained scientist in order to participate.
WHY YOU SHOULD TRY IT
Citizen science is great to do with students because:
Ready to try it out? Here is a list of websites and project ideas to get you started.
1. CitizenScience.gov is a government website that has a TON of project ideas and is a great place to start. You can collect data that will be used by NOAA, USGS, National Science Foundation, and even NASA.
2. The Great Backyard Bird Count is a website run by the Audubon that encourages students to get outside and start birding. They are looking for regional data where people can upload pictures and species of birds they see in their neighborhoods. Time to dust off those binoculars!
3. National Geographic has a list of citizen science projects, ranging from wildlife observation, measuring night sky brightness (light pollution), butterfly census, listening for frog and toad calls, and more.
4. SciStarter.org is a website put together by Arizona State University and the National Science Foundation. You can search for projects near you or online only.
5. Project Green Challenge is a website that gives students environmentally-themed challenges. You can register your school and enter to win prizes!
6. Zooniverse is "people powered research." This website has a ton of ongoing projects that also venture into other content areas outside of the natural sciences.
7. inaturalist Do you ever take pictures of insects and cool species in your yard or neighborhood? inaturalist is a website (and phone app) that allows you to upload pictures of your findings and share/discuss with fellow naturalists.
8. Captain Planet Project Hero is a PBL driven website where students can help threatened species and ecosystems in their area.
9. The GLOBE Program is looking for people to contribute data for cloud types, mosquito habitats, and land cover observations.
10. Project Budburst was created by Chicago Botanical Garden. Their goal is to uncover the stories of plants and animals affected by human impacts on the environment.
11. Gorongosa Webcams If you've ever used curriculum from Biointeractive, you know it's pretty stellar. In this lesson students study webcams from Gorongosa National Park in Mozambique and do animal identification.
12. Pollinator Live is a website that includes links to a bunch of citizen science projects centered around attracting and monitoring pollinators in your area. Teach students the importance of pollinators!
Looking for low stress and low prep ideas as we navigate distance learning? Here are 5 ideas you can use with your secondary science students:
1. CLICK HERE to check out virtual field trips your students can explore!
2. CLICK HERE to see a full list of science related movies, TV shows, and documentaries.
3. Check out American Chemical Society's blog post on kitchen chemistry ideas!
4. Have students create a photo journal!
5. Have students build something out of recycled materials. Ideas could include a rube goldberg contraption, a parachute, or a solar cooker.
Hope those tips help you through this tough time!
It can be frustrating when students are absent on lab days. You spend a lot of time setting up and often spend money out of your own pocket for supplies. If you are doing labs often or teach multiple preps, dealing with student absences just gets harder to juggle. By the time the student comes back and asks "what did I miss?" I've often torn down the lab or passed the supplies onto another teacher in my department and don't have them available. Instead of scrambling to re-set up the lab every time, here are a few alternative options:
1. DO THE LAB MAKE-UP ON THEIR OWN TIME
If the lab isn't super labor intensive and students can read through the procedures on their own to figure out what to do, I have them come in and make up the lab on their own time. Luckily my school has an advisory period built into the school day where students can travel to get caught up on their classes. If you don't have this luxury, they could come in during lunch or after school.
2. SUBSTITUTE THE WET LAB FOR A VIRTUAL LAB
There are a bunch of virtual labs out on the internet that you could substitute for the wet lab. Phet or Glencoe are great options to check out.
3. COPY THE LAB DATA FROM A PEER AND ANSWER THE ANALYSIS QUESTIONS
This option is my go-to for labs that take multiple days. If students missed the first day of experimental design or data collection, they can come back in, join a lab group, and finish the lab. If it was a one day lab, you can have a "master copy" of data that absent students can copy down and analyze before answering the post lab analysis questions.
4. DO AN ALTERNATIVE ASSIGNMENT ON THE SAME TOPIC
If you can't find a virtual lab on the same topic, try and find an article or worksheet on the same topic and use that assignment to replace the lab grade. Newsela is a great place to find free non-fiction articles. Don't forget to look for freebies on TpT! (type in the topic you are looking for and filter by grade and cost).
5. EXCUSE THE ASSIGNMENT
I would like to begin with a disclaimer that this is NOT something I do regularly. I think students need to somehow show proficiency on a standard, not just get it excused. However, if a student tells you they were absent for a week because they were in the hospital or had a true family emergency that you can verify, sometimes they just need to be cut a break. Realize they will have missing assignments from 6 other classes on top of yours, pick which assignments you think are vital for mastering the standard, and excuse the rest.
The moral of the story: Don't lose your sanity trying to have every absent student do make up labs.
I posted on Instagram last week pictures of preparing agar for my go-to first week of school lab: testing the 5 second rule. It’s a great lab for back to school because students are super engaged and it’s a good way to review variables and how to set up a controlled experiment. I had a bunch of people ask questions about how I prepared the agar and set up the lab, so here is a blog post to answer all your questions!
WHAT MATERIALS WILL I NEED?
-Sterile petri dishes
-Dehydrated nutrient agar
-Hot plate with stir capabilities
-Heat resistant gloves
-Optional: Autoclave and incubator
DO THEY NEED TO BE STERILE? DO I NEED AN AUTOCLAVE?
If you want to have accurate data, yes, your petri dishes need to be sterile.
Each year, I open a new sleeve of plastic petri dishes so I can assure they are sterile. If you don’t have access to new ones you can re-use petri dishes, but make sure to either sterilize them in an autoclave or clean them thoroughly in a bleach solution followed by a distilled water rinse.
HOW DO I MAKE AGAR PLATES?
Methods will vary slightly depending on the agar you ordered, (directions should come with your nutrient agar, or should be available online from the vendor) but here is the general process:
1. Measure out the desired amount of nutrient agar and distilled water and pour into a clean beaker. For the agar I order, the recipe calls for 23g of dehydrated agar per 1 liter of distilled water. (Note: 1 liter of agar will fill roughly 30 - 40 petri dishes).
2. Add a stir magnet to the beaker and place on your hot plate. Turn on both the heat and the stir settings.
3. Continue to heat and stir your agar until it is boiling. This may take a while, but be patient- if you don’t wait for it to boil, your agar won’t solidify once it cools.
4. If you don’t have access to a hot plate, you can use the microwave. Place beaker and agar mixture into the microwave and heat for 3 minutes. Continue heating in 1 minute bursts until the agar is completely dissolved and the mixture begins to boil.
5. As you are waiting for the agar to boil, lay out your sterile petri dishes on a heat resistant counter. Keep the lids on as much as possible to avoid any contamination.
6. Once agar has come to a boil, remove from heat using heat resistant gloves. Lift the lid on a petri dish, carefully pour agar into the petri dish until it is roughly 2/3 of the way full, and promptly return the lid. Continue until all your agar has been used.
7. Allow the agar to solidify at room temperature- this shouldn’t take more than 15 minutes.
8. Once the agar has solidified and cooled, store them upside down in the fridge until you are ready to use them. Storing them upside down will ensure that any condensation drips onto the lid, not onto your agar.
HOW MANY DAYS BEFORE USE CAN I POUR THE PLATES?
I typically pour the petri dishes a day or two before I need them and store them in the fridge. Petri dishes in the fridge will be good for a few weeks before they begin to dry out, but the sooner you use them the better.
I HAVE 150 STUDENTS. HOW MANY PLATES WILL I NEED TO PREPARE?
It can be pricey to pour a ton of plates every year and with 150 students it would be way too expensive (and a lot of work!) to pour every student their own plate.
When I do this lab with my students, I put them in groups of 4. With roughly 32 students per class, I pour 8 plates per class. As a lab group I let them choose a variable to test and have them whiteboard their experimental design. Some groups want to change the amount of time the food is on the floor, other groups want to test different food types, and other groups want to try out different dirty surfaces. Once I’ve approved their design (to make sure they have a control) they can begin the lab.
DO I NEED AN INCUBATOR?
Okay, so your students set up the lab, but do you need to leave them in an incubator?
If you want quick results (overnight) then an incubator will speed up the process. But if you don’t have access to one, just let the plates sit for an extra day or two in your room temperature classroom and you will still get plenty of bacteria growth. Again, leave them upside down (agar side up) so you don’t have issues with condensation dripping into your agar.
HOW TO STUDENTS COLLECT DATA?
Since I do this lab the first week of school, this is an excellent time to review the difference between quantitative and qualitative data. Once students get their plates back, I have them make both qualitative observations and measure quantitative data.
You can have students collect quantitative data by counting colonies, but a much easier way is to use a grid and calculate percent coverage. You can purchase gridded stickers that stick onto your petri dish lids, or just do it yourself with a fine point sharpie marker. All students have to do is count the number of squares that have bacterial growth, divide it by the total number of squares, and multiply it by 100 to turn it into a percentage.
HOW DO I DISPOSE OF THE PLATES?
It is important you do not place your plates in the trash without first taking some precautions. While bacteria in small numbers may be harmless, once cultured into millions of cells they can pose a greater threat. There are a few ways to properly dispose of your used agar plates, depending on what you have available:
1. If you have an autoclave, you can autoclave your plates per the directions on your autoclave (generally at least 30 minutes).
2. If you used glass petri dishes and don’t have an autoclave, prepare a 20% bleach solution and spray your plates down. Allow the bleach to soak into the agar for 1 hour before placing agar in the trash. Then thoroughly clean your empty petri dishes again with a bleach solution and distilled water rinse.
3. If you used plastic petri dishes that you can afford to part with, you can place them in bio-hazard bags and have your district arrange for bio-hazard pick up. It doesn’t hurt to spray them down with a 20% bleach solution before placing them in bio-hazard bags.
I hope that answers all your questions! If you are interested in the lab handout I use with students to test the 5 second rule, you can find it HERE!
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. Dialysis tubing can be purchased from science suppliers or is also available on Amazon.
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.
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!