At the beginning of every school year I can bet that you review the scientific method. While there isn't necessarily a specific set of steps that we follow in all branches of science, we want our students to be able to use inquiry and think through the scientific process. One great way to get our students thinking like scientists is by using the CER method.
What is CER?
CER stands for claim, evidence, and reasoning. After being posed with a question or observation, students have to make a claim (similar to forming a hypothesis), provide evidence to support their claim, and explain their reasoning. Getting students to understand CER is important because it helps them think through the scientific process. All claims must have supporting evidence, and students should be able to explain the reasoning behind their thoughts. CER is science literacy for the win!
CER can be applied so many different methods of teaching. It doesn't just have to be for labs! Here are a few ideas on how you can implement the process:
1. Video clips: Find a video clip that poses some sort of question or claim. Have students identify the claim, evidence, and reasoning given in the video. If only a claim is given, have students come up with evidence and reasoning on their own following the clip.
2. Labs: CER is great to implement within the lab process. Students are posed with a question they will test, write out their claim (hypothesis), provide evidence (their data), and reasoning. If you haven't checked out NSTA's ADI books (arguement driven inquirty), they follow the CER process and have a lot of great lab ideas. Many of the labs can be found free online, but you have to purchase the book to get the accompanying teacher information. Some free resources can be found at the following links: Biology labs, Chemistry labs, Middle school life science
3. Socratic Seminars: If you aren't familiar with what a socratic seminar is, it is essentially a class discussion where the facilitator asks open ended questions and encourages class discussion. For me it works best when the class sits in a circle facing each other, and every student is required to contribute to the conversation at least once (give them a grade for speaking). Pose a question to your class, give them time to come up with CER speaking points, and get them talking! Make sure your question is open ended so students don't all come to the same conclusions. A sample question you could pose is "Do you think humans could ever survive on Mars?" While there are only 2 answers to this question (yes or no), there will be a lot of discussion regarding their evidence and reasoning.
4. Whiteboard sessions: CER works well on mini-whiteboards. I have studentes set up the whiteboards as pictured below. After groups fill out their whiteboard, have the class face each other in a circle, review the boards, and have a "whiteboard session" where they discuss what other groups came up with. This could supplement a lab or be done as a stand alone activity. It takes some training to get students to give constructive feedback to other groups, but after a few tries they get the hang of it. A sample is shown below.
5. Analyzing journal articles: We all want our students to be better readers. At the high school level, I try and get my students reading journal articles. They can be a lot to digest and asking students to read and summarize them can be daunting. I give students the CER graphic organizer (found below) and have them fill it out as they read. It is a great way for them to organize information as they read.
This is a great inquiry lab for your physics unit! In this activity students will be asked to figure out which of the following variables affect the period of the pendulum swing: the mass, the length of the string, or the angle the pendulum is released from.
All you need for this lab is: string, a ring stand (or other object to hang the string from) a stopwatch, a protractor, and some hanging masses. Don't have hanging masses? You can hang a cup instead and add pennies or marbles for weight (see the images below).
I gave the students 2 days to complete this lab. The first day they just played around with the pendulums and tried to figure out which variable affected the pendulum swing. The second day I had them time the swings, record data, and make conclusions. It was a great introduction to my unit on motion! If you'd like to check out the 2 day lab write-up I made, it is available in my TpT store.
I hope your students enjoy this lab as much as mine did!
Physics is really exciting to teach because there are so many fun labs you can do. After teaching students about speed, velocity, and acceleration I wanted to do a STEM lab to follow up the unit. I decided to have students build a parachute out of a plastic grocery store bag and gave them a goal of keeping it in the air as long as possible. It was not only fun for them but the materials were super inexpensive! I supplied string and tape, and they had to supply the bag and any other materials they wanted to add. You are welcome to set size or material restrictions but I chose not to. I gave them one class period to build (if they didn't finish they had to finish at home) and we tested the following day. When testing the parachutes I tied a GI Joe to the bottom to add some mass but you are welcome to use whatever you have handy (metal washers work great too).
Our school is 2 stories so the students dropped their parachutes from the 2nd story. When they went to drop the parachutes they had 1 rule: No throwing the parachute up in the air. They had to hold their hands straight out horizontal and drop straight down.
Each group got to drop their parachute 2 times. They had to calculate the speed of the drop (distance / time) and acceleration (Vf - Vi) / t. Overall they had a blast and I had some silly prizes for the winner of each class period. If you would like to check out the lab worksheet I used CLICK HERE. Have fun!
Virtual labs are a great tool to try if you have computer access. I love them because:
I've compiled a list of websites that have virtual labs. Many require Flash or Java software, so be sure your computers have it before trying with students. If any of the links are broken or out of date, please leave a blog comment and I will update.
Enjoy! If you know of other sites, please share in the comments!
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I'm excited to share with you an EASY PEASY way for students to see osmosis in plant cells! In the past, I always used elodea leaves for this lab. Elodea can be hard to find at pet stores and is a little temperamental to keep alive. This year I decided to use onion skin from a purple onion and we got awesome results!
I used this lab BEFORE I taught any vocabulary such as osmosis, equilibrium, hypertonic, hypotonic, or isotonic. I wanted students to visually see what happens to cells in fresh water vs. salt water before I threw any vocabulary at them. Students were really excited to see the cells change within a matter of 60 seconds. Here are a few tips when doing this lab for the first time:
1. You cannot use the dry layers of the onion skin. You need to use the very top of the purple fleshy layer. It can be a little bit tricky to get a specimen that is thin enough, so I decided to do it myself and hand each kid a piece. I took metal tweezers, gently pushed them under the purple layer, and slid the tweezers out so a small flap of onion skin was loose. I peeled it off, handed it to each kid, and they set up their own wet mounts. No dye needed!
2. Have students make drawings using fresh water first. After they finished their drawing, they switched to salt water. Make sure your salt water solution is pretty saturated.
3. Tell students to wait at least 2 minutes before drawing the salt water image, because sometimes it takes a little time for the cytoplasm to shrivel up. Below are images of the onion cells in fresh water (left) and salt water (right) on 100x magnification. We had a discussion on whether or not the cell wall shriveled as well. Students automatically said yes, because the cell wall is almost transparent and harder to see. Once I told them to switch to high power (400x) they were able to see the cell wall more clearly and realize that the cell walls were still intact, while the membrane and cytoplasm shriveled.
Tomorrow we are going to follow up with the discussion of what happened and why. Students will take notes on osmosis and we will relate it to real world situations such as: Why can't I drink salt water if I'm stranded on a boat in the ocean? Why is my contact lens solution saline instead of pure water? Why do grocery stores spray the produce with water? If you want a quick worksheet to use as a formative assessment to follow this lesson, check out my tonicity and osmosis worksheet in my TpT store HERE.
I hope your students enjoy the lab as much as mine did! Other than having my classroom smell like onion for a day, it was a total win!
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As fun as prepared slides are, students always LOVE looking at living organisms under the microscope. I generally order mixed protist specimens from Wards or Carolina Biological, but this year I didn't get an order put in on time (if your district is like mine it often takes months to get things ordered and delivered...) Since I didn't have anything for my students to look at, I decided to make a hay infusion. It turned out great for what I needed.
Overall, here are the pros and cons of doing a hay infusion:
Before using the hay infusion, have your students practice using the microscope with prepared slides. If students are comfortable with how to focus and scan, it makes it much easier when they are looking for things that are swimming around. We began the class with learning how to set up a wet mount slide using an elodea leaf. Once they got the hang of it, they cleaned their slide and took a sample of the pond water.
Here is a video I took under 40x magnification:
and 100x magnification:
Although there weren't a variety of species to see, students were still pretty excited to see them swimming around. I wasn't able to identify which type of protists we had- if you had honors or AP students it might be fun to give them a protist dichotomous key and see if they can figure out which species they find. Overall it was a success and didn't cost me a cent!
Okay, so you can tell by the title of this blog post I'm a biologist and not a chemist. (Chemistry teachers, please don't send me hate mail!) Honestly, I don't love chemistry and I don't love teaching it. BUT, I realize how important it is for students to understand biochemistry before I dive into a fun enzyme lab. There have been years where I thought "screw it, I'm just going to talk about macromolecules and cells without reviewing atoms and bonding." Oh was I sorry. Most of my students didn't have a strong enough chemistry background to understand polarity without reviewing bonds. Although most of my students took chem-phys the previous year, they didn't understand how the chemistry they learned prior could apply to biology. So my advice is to take it slow, review the periodic table and bonding, have them build models, and really understand the structure of the 4 macromolecules before moving on in your cells unit. Once you get to membranes, they will understand them so much easier if they understand lipids. Once you get to DNA structure they will understand why it runs from 5' to 3' if they understand the structure of a nucleotide. They will also understand DNA replication and the enzymes involved so much better if they understand protein structure and folding. Have I convinced you yet? I hope so. Here are a list of fun ways to teach macromolecules and deepen student understanding:
1. Build Atomic Models. I'm lucky enough that I have access to model kits. I have my students build models of all the macromolecules. The best is when they can each build an amino acid, link them together, and see dehydration synthesis with their own eyes. Check with the chemistry teacher on your campus and see if they have kits you can borrow for a few days.
2. Emphasize Protein Folding. Lets be honest- of the 4 macromolecules, proteins are the rock star. It's so important that students understand how and why proteins fold, and the consequences of them denaturing. My school purchased a kit called "protein toobers" where students pretend the "toober" is a long chain of amino acids. (The activity can be purchased HERE. I am not affiliated in any way with this company). Students add thumbtacks (side chains) and then have to fold accordingly. For example, if white thumbtacks are hydrophilic and yellow thumbtacks are hydrophobic then they need to fold the toober so the white thumbtacks face out and the yellow thumbtacks face in. It is fun for them to see that each group's protein is folded differently based on the order they placed the thumbtacks. If you aren't able to purchase this kit, I think it could easily be replicated with pipe cleaners and pony beads (click here to check out a similar product from Science with Mrs. Lau!)
3. Use Videos. It is always helpful for students to hear things explained more than once and in a variety of ways. Find videos that will help reinforce concepts already taught. Amoeba Sisters always have great videos and worksheets that go with them. Here is a link to the video on biomolecules and the associated worksheet.
4. Engage with Labs! There are a bunch of fun labs out there on macromolecules, especially enzymes. I love this liver enzyme lab from biology corner. Students will see how changing temperature and pH will affect enzyme reaction rates. It's not the most fun lab to clean up after, but it's inexpensive and fun for the students. You can buy a tub of chicken liver from the grocery store for less than $2 and that will last you the entire day. Tip: I've found I get the best results when I puree the liver in the blender instead of just cutting it into pieces.
5. Use Review Activities and Games. I have never met a student that didn't love puzzles and games. It is way more fun to use these as formative assessment tools opposed to a study guide. I have a few available in my teachers pay teachers store I think you will enjoy! One is a macromolecules tarsia puzzle (pictured) where students have to pair up words with their definitions. Another option is a memory game where students flip over 2 cards at a time to try and find matches. I also have a flip book which is a fun review tool for interactive notebooks. Don't miss my macromolecules bundle where you can buy them all at a discounted price!
What other fun ways do you teach macromolecules? Leave them in the comments!
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Living? Nonliving? Dormant? Dead? Even though teaching living vs. nonliving seems very elementary, you'd be surprised by how often high school students get confused when you throw examples at them. It makes me think of this 90's "J-E-L-L-O it's alive!" commercial:
But in all seriousness....
Teaching characteristics of life is a great way to start off the year in biology. I like teaching it week 1 because it's more fun than the scientific method (which they should know by now anyway) and a great introduction to biology- the study of living things. Here are a few resources you can add to your teacher toolkit for your life unit:
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This is one lab that you don't want to miss! It's easy, the materials are inexpensive (you probably already have them at home), and it ties together multiple concepts. Winner!
In this lab, students will analyze a pedigree of a fictitious family. In the introduction, students read that "Jon and Sue Smith" were in a car accident and need a blood transfusion. The hospital asks family members to donate, but students will need to figure out which family members are able to successfully donate. To complete this lab, students will need to understand blood types, punnett squares, and pedigrees. Its a great end-of-the-unit lab when you are finished with genetics.
One piece of feedback I have gotten from my TpT store is that this lab can take a while to set up. I'm here to give you some tips to save you set up AND clean up time.
This is a great lab! But don't just take my word for it:
"A+ lab, I can't tell you how well this lab is planned out. There are great teacher instructions (for once!) and a great student lab handout/key. Everything that I need to have a successful lab and not take me 30 hours to figure everything out. I would definitely buy labs from Science Rocks." -asuzanneg
"So fun! My students had a blast. Very well organized and easy to follow. Thanks!" -Sarah H.
This lab is one of my top sellers in my Teachers Pay Teachers store. It is easy to set up and doesn't require a lot of materials. However, I frequently get questions about the lab so I'm hoping this blog post will be useful to those teachers out there who about to set up this lab.
In this lab, students will be testing whether or not aquatic plants do photosynthesis in the dark or light, and also testing if they do cellular respiration during the dark or light. The plant I usually use for this experiment is called elodea, which is available at any local pet store in the fish area. One nugget of information you will need to know- pet stores call it anacharis, not elodea. It is usually sold in bunches of 4-5 stems for a few bucks. Two big bunches should get you through the day. If they don't have elodea, any other aquatic fish tank plant will work fine, but make sure it is a tall skinny plant that will fit down into your test tubes.
One reason this lab is great is because it can be used in multiple places in your curriculum:
~ Cells unit: When you are teaching cells, chances are you will be talking about chloroplasts and mitochondria. Along with these organelles you will be discussing photosynthesis and cellular respiration. This lab fits in great because it shows that plants not only do photosynthesis, but cellular respiration as well.
~ Ecology unit: During my ecology unit, we cover the 3 major biogeochemical cycles (water, carbon, and nitrogen). What better way to talk about the carbon cycle than to demonstrate the relationship between plants, animals, and gas exchange?
A little background....
This lab uses the chemical bromothymol blue. This chemical is used as a pH indicator. When the pH is above a 7 (basic) it is blue, but when the pH drops below 7 (acidic) it starts to turn yellow.
Image below is courtesy PureySmart on Wikimedia Commons.
Before beginning the lab, I like to demonstrate to the students how bromothymol blue works. I get 2 erlenmeyer flasks (beakers will work just fine too) and fill them 3/4 of the way full with water. Add enough bromothymol blue for the water to be visibly blue. (In a beaker of 200mL of water, I add about 4mL of bromothymol blue). Call up a student, and have them blow through a straw into the beaker. As they blow (it will take 3-4 big breaths) the water will slowly change from blue to yellow. This is because when the carbon dioxide in our breath reacts with the water it forms carbonic acid, lowering the pH.
Inquiry, Inquiry, Inquiry
When I do this lab, I do not tell students how to set up the experiment. I split the class into lab groups, and assign each group one of the following questions:
1. Do plants to photosynthesis in the dark?
2. Do plants do photosynthesis in the light?
3. Do plants do cellular respiration in the dark?
4. Do plants do cellular respiration in the light?
Obviously the group that gets assigned "do plants do photosynthesis in the light" will know the answer, but they will still have to set up a controlled experiment that can demonstrate it. I give each group a big white board and have them set it up like the image below. They will have to fill it out based on the specific question they are assigned. If you don't have whiteboards, butcher paper works great too. Students will know what materials they have to work with because they are listed on their lab worksheet (available in my TpT store).
As we walk around the room and discuss experimental design, students will begin to see that each group will set up their test tubes the same way, the only difference being if their tubes get left in the light or wrapped in foil and put in the dark for 24 hours.
Two notes: I get asked how much bromothymol blue to add to the test tubes. I have each group add 1mL to each tube. If you would like to add more or less that is fine, as they add the same amount to each test tube for consistency. Also- make sure to fill the test tubes to the top and cap them tightly, or use parafilm to cover the tops. We want the gas to stay in the water, not escape.
When students come in the following day they will pick up their test tube rack and fill out their data tables on what happened. They will see that the elodea did photosynthesis in the light, and cellular respiration in the dark.** (see note below)
**One thing you will have to discuss with your students: Plants are doing cellular respiration in the day time as well, but since photosynthesis is also occurring the indicator stayed blue.
A great extension activity is to add aquatic animals to this experiment and see how the added respiration affects the color change. If you can get your hands on some small snails, they will fit great into the test tubes. I had trouble finding snails in Arizona, so I went to my local pet store and picked up two feeder goldfish. I filled up two large Erlenmeyer flasks with water and bromothymol blue, and turned one yellow. I added elodea and a goldfish to each flask. Next, I asked my students what will happen when we leave these in the light for 24 hours. The next day we came in and saw both flasks were a shade of bluish green (somewhere in the middle of where the two flasks began). If you don't add a ton of bromothymol blue, and only leave the fish in for 24 hours the fish will not be harmed.
Hopefully you are ready to start this experiment! If you have any questions, drop them in the comments below!
Hear what customers have to say:
"Awesome! The students who really worked to seal the containers with no air in them were richly rewarded with their results." -Susan M.
"This is a great guided inquiry lab. I love giving students freedom in their experiment design while still ensuring the overall concept is understood." -Crystal D.