Lab: Determining the Density of Unknown Metals

Click on picture to download this lab for free.

Here is a brand new FREEBIE for you!

I have a friend who is a newly starting science teacher in our local middle school.  She has many years of teaching experience, but is new to the wonderful world of science.  Due to all sorts of factors beyond her control, she has been teaching a science class this year.  The textbook being used is neither life science nor physical science, but a spiraling mix of both.

Most of you know me as a biology teacher, but in my 28 years of high school teaching, I have taught chemistry classes for at least 15 of those years.  This week end my friend needed help, so together we came up with this idea for a simple lab that she could do.

I have added this lab to my store on TeachersPayTeachers.com, but it is FREE for the taking.  I hope that it will benefit many of you.  Just click the link below to download.

Lab: Determining the Density of Unknown Metals

The materials list for this lab is simple:  a balance, a graduated cylinder, and different pieces of metal.  You can use any metals that you might have available.  Most middle and high school labs will have pieces of aluminum, copper, magnesium, lead, and zinc.  This lab will work with whatever you have available.

The idea is very simple.  Students will determine the mass and volume of the metal strips, and use this data to calculate the density.  The student does not know the identity of the metal.  From a list of densities provided, the student will determine the identity of each metal.  We added 12 analysis  and follow up questions that are thought provoking and require some critical thinking skills.  And since standardized testing is almost upon us, we added a graphing exercise (involving density) to reinforce the graphing skills that were taught earlier.  Here is a quick look at a few of the pages.  An answer key is provided with the download.

Enjoy this new freebie and Happy Teaching!

Also related:

Matter and Change Unit Bundle

Matter and Change PowerPoint

Matter and Change - Four Mini Labs

Citizen Science.....Revisited....Get Involved!

Back in December, I wrote a blog article on Citizen Science from the Scientific American website.  (Click here to read the original blog post.)  I like this idea so much that I wanted to follow up on it.

This week end you can participate in The Great Backyard Bird Count.  This event will be taking place from Friday, Feb 17 through Monday, Feb 20.    From their web site:  "The Great Backyard Bird Count is a 4 day event that engages bird watchers of all ages in counting birds to create a real-time snapshot of where the birds are across the continent.  Anyone can participate, from beginning bird watchers to experts.  It takes as little as 15 minutes on one day, or you can count for as long as you like each day of the event.  It's free, fun and easy - and it helps the birds".

It is not too late to sign up.  You can find all of the information here.

What is the count used for?  The data is used by scientists to answer questions about populations, migration patterns, the effect of environmental influences on populations, how weather patterns affect populations, and much more.  The details can be seen by clicking the link above.

We do not have school on Monday since it is President's Day.  I am the sponsor of the science club at our school.  The 30 member science club is meeting at our local animal shelter on that day for a day of community service.  We will be raking, cleaning up the outdoor play areas for the dogs, scooping poop along the walking trail, and no doubt cleaning out animal cages of all types.  But we will also be participating in the Great  Backyard Bird Count.  Our animal shelter is on the edge of town in a wooded area.  I just hope we will be able to identify and count the numerous birds that we will see!!

This is a fabulous activity for the entire family and it is not too late to sign up and join in on the fun!  Plan an outdoor event with your family this week end and include the Great Backyard Bird Count as part of your activities.

 Finally, I want to share this new link with you.  This is an article I just read on Nature.com.  It is called, "Citizen Science Goes Extreme."  This was a well written and very informative article about the need for citizens world-wide to participate in scientific research and the preservation of habitats.

What Can A Biology Teacher Do On Valentine's Day?

The only time I regret being a high school teacher is around a holiday. 

Don't get me wrong.... I love teaching high school biology, and I particularly love the teenagers that I teach. But, I see the elementary teachers doing so many cute and fun activities that just look so adorable!  And they have incredibly cute decorations for every season! Sigh..... I only have my collection of Einstein posters haphazardly stuck around the walls. In high school, there are generally two problems with celebrating the different holidays in our classrooms: One, the students think they are too cool and too grown up to be doing silly kid stuff. And two, if "it" is not on the blasted standardized test at the end of the year, then woe be unto you who deviate from the "you must teach to the test" curriculum plan!!

For me, it just so happens that I usually manage to be teaching the circulatory system around Valentine's Day. Although not nearly so fun as exchanging valentines and getting lots of treat bags, at least it does involve the heart. One of my favorite labs is Measuring the Heart Rate in Daphnia. It is a 2-part activity. In the first part, students explore the effect of temperature on heart rate. The second part is a student-designed experiment in which students test a different variable to see the effect on the heart rate. It is a really fun lab and students love it. Click the red link above or the image below to view in my TPT store.

Granted, the above lab takes some planning and probably takes 2 class periods to complete. If you are looking for something quick, and very easy, how about my Science of Valentine's Day video from my YouTube channel, the Amy Brown Science Learning Lab? The 4-minute video is free for your classroom use. I also wrote a fun acrostic puzzle activity to accompany the video. Students will answer questions to decipher three really corny Valentine jokes. Click here or on the image below to view the puzzles.

Finally, for the chemistry teachers, I have a Color by Number activity with a Valentine's Day theme. Students will practice writing chemical formulas and naming compounds while uncovering the hidden picture.  Click here or on the image below.

How about this lab activity?  This activity is called Crystal Hearts and looks like it would be a lot of fun.  It doesn't really fit in my biology curriculum, but it would be great for a middle school general science class or a high school physical science class.

Measuring Heart Rate in Daphnia

Watch Their Hearts Beat: A Daphnia Lab That Brings Biology to Life

An Unexpected Star in the Biology Lab:  Need a classroom lab that’s easy to set up, exciting to run, and packed with teachable moments? Meet Daphnia—a tiny aquatic crustacean with a see-through body and a heart you can actually see beating under a microscope. It’s weird. It’s wonderful. And it’s the perfect hook for teaching circulatory systems, environmental effects on physiology, and graphing real data.

This Daphnia heart rate lab checks all the boxes for a super-engaging, low-prep biology investigation. Students get hands-on experience with live organisms, observe real-time physiological changes, and collect data that sparks discussion and curiosity. This lab encourages deeper thinking, reinforces graphing skills, teaches the scientific method and experimental design, and turns abstract textbook concepts into visual, measurable experiences.

What Students Discover: When Daphnia are placed in environments of varying temperatures, their heart rates respond—dramatically. Students watch as these tiny creatures go from chilled-out to heart-racing, helping them understand the link between metabolism and temperature in ectothermic animals. 

Even better? Students can extend the lab activity by designing their own experiment to test a different variable —testing how caffeine, pollutants, or pH levels influence heart rate. Honors and AP students can take it further by calculating Q₁₀ temperature coefficients, analyzing their results like real researchers.

Please note: Teach students to respect all living organisms. No harm should come to the Daphnia in this experiment.

This isn’t just a fluff activity. The Daphnia heart rate lab builds core science skills:

• Graphing and analyzing data
• Comparing variables and controls
• Designing and running investigations
• Problem solving and critical thinking

It also supports NGSS and AP Biology objectives, from cellular processes to environmental impacts on organisms.

The biggest problem with this lab is helping students find the heart. The digestive system of Daphnia is quite active, and the students often think that the moving digestive system is the heart. The heart is located just behind the head on the dorsal surface of the body.  It will appear as a very small, clear and transparent, beating sack.

Classroom-Ready, Teacher-Approved: Looking for something that won’t eat up your prep time? This Daphnia heart rate resource comes with the following.

• Clear student worksheets
• Ready-to-go graphing templates
• Background reading for context
• Optional extensions for advanced learners
• A teacher guide to make implementation a breeze

Ready to Try It?

This lab isn't just about watching hearts beat—it’s about getting your students excited to learn. Whether you're teaching standard biology, honors, or AP, this investigation delivers science that sticks.

👉  Click here: Measuring the Heart Rate in Daphnia

The benefits of this lab? 

• Labs keep the student excited and interested in science.  
• If the student views your class as "fun", they are more likely to perform well in the parts of the class that are less fun.....think lecture days.
• Working with living organisms is a fundamental part of a biology class and should be included at every opportunity.
• Students gain an appreciation for the living world when they get to view organisms that they are unlikely to see or notice in nature.

What do you do with the Daphnia when the lab is over?  Well, our Daphnia will spend the remainder of their days in my Elodea tank!

The Effect of the Enzyme Amylase on Starch

This is a fun lab that students enjoy and it teaches important concepts about enzymes.

Make your biology class more appealing and exciting by incorporating a variety of fun and interesting labs into your weekly lesson plans.  This inquiry-based lab allows students to discover basic information about the functioning of enzymes within cells.  Enzymes are biological catalysts that speed up the chemical reactions within cells.  Without the aid of enzymes, the chemical reactions of the body would proceed so slow that the reaction would be of no use to the cell.

Purpose:  In this lab, the student will observe the effect of the enzyme amylase on its substrate, starch.  The student will perform various experiments with the enzyme amylase and will compile a list of facts concerning enzymes.

Students are given the task of trying to determine what happens to starch in the presence of the enzyme amylase.  There are essentially four mini-experiments in the lab that will lead the student to the appropriate conclusion.

1. The student mixes together a solution of of amylase and starch and determines the length of time it will take until the starch has been completely broken down into end products.  This is done by removing a drop of the solution each minute and testing it for the presence of starch.
2. Now the student must determine the end products of the reaction.  Benedict's solution is used in this second portion of the lab to determine that the end product is a simple sugar.
3. In the third portion of the experiment, students use glucose test strips to determine that glucose is NOT one of the end products.
4. Finally, the student will test the solution for the presence of proteins to determine that the enzyme is still present when the reaction is complete.

This lab is designed for a typical high school biology class for students in grades 9 – 12.  It is appropriate for both standard and honors classes as well as for first or second year biology students.  I have used this lab in both my freshman biology I class as well as my AP biology class.

Happy Teaching!

Teaching Cellular Respiration

You have reached the point in your biology or life science class where you must teach cellular respiration.  Do you approach it with dread and trepidation, or do you get all energized and excited?

For many teachers, it is the former.  The negative thoughts start swirling in their head:  "This is so hard for the students.  Students hate this topic!  They never understand what I am trying to teach!  How can I explain this in a way they can comprehend?"

In my first years as a biology teacher I felt exactly like this.  But now, cellular respiration is one of my absolute favorite topics to teach!  And when I am excited about the topic, my students get excited about the topic. Cellular respiration is a topic that cannot be skipped or glossed over in your biology class.  Cellular respiration is the conversion of food into a form of energy the cell can use.....ATP!  All living things perform cellular respiration and it is fundamental to the study of biology.

How do you teach this to your students?  I have several suggestions for how to make this a fun and interesting topic for your students.

1. First of all, you, the teacher, must have a thorough and complete understanding of the material you are about to teach.  After teaching for 28 years, I still study the topic each year before I teach it.  I try to anticipate the questions that students might ask, and I make sure that I can answer their questions accurately and with a vocabulary they can understand. Remember, if you are not sure about the processes that are taking place within the cell, you will not be able to explain it to your students.  Once the students are "turned off" on a topic, it is very hard to get them back. Bottom line?  You need to study and know what you are talking about!
2. Don't oversimplify the process.  Many teachers try to make the process of cellular respiration as simple as possible for their students.  Obviously, we are not teaching a college level class in cell physiology, but we need to include enough detail so that the chemical pathways of glucose make sense.  I try to avoid using the very complicated charts and diagrams found in the biology textbooks.  After all, we want our students to know the main ideas of each stage of respiration.  They do not need to know every minute detail, but they do need enough detail to understand the process.  I drew my own diagrams for each stage of respiration showing the key points of each chemical reaction.  My students enjoyed having these outlines to fill in as I taught the lesson.

This digram gives the basic details of Glycolysis

This digram gives the basic details of the bridge reactions.

This digram gives the basic details of Krebs cycle.

My final bit of advice....make sure you include some hands-on activities while teaching this material.  

Here is one very simple activity that I do with my biology students:  I place all of the keywords of respiration on pieces of card stock paper.  Each word is then laminated to be used year after year.  The key words I use include: glucose, PGAL, pyruvic acid, ADP, ATP, NAD+, NADH, Coenzyme A, acetate, oxaloacetic acid, citric acid, FAD, FADH2, CO2, cytochromes, electron transport chain, hydrogen, ATP synthase.  Each group of two student gets a set of words.  Students are asked to arrange and order the words to show the entire process of anaerobic and aerobic respiration.

My latest project has been to develop a set of notes for the teacher and a set of notes for the student on cellular respiration.  Once the notes were refined and polished, I put together a 72 slide PowerPoint presentation on cellular respiration.  Over a month in the making, I was both relieved and excited to have this project finished.  I am very pleased with the result.  My students enjoyed the unit on respiration and I think they came away with a far greater understanding of the process than my former classes.

Here is the link if you want to check it out:

Cellular Respiration PowerPoint with Notes for Teacher and Student

Lab: The Effectiveness of Antiseptics and Disinfectants

Do they really work??

Our biology I students have completed their lab on "The Effects of Antiseptics and Disinfectants on Bacteria Growth".  The results turned out great and the students had a great time growing the bacteria.  Many were very surprised by the results of the lab!


We inoculated each dish with soil bacteria.  Each student had three Petri dishes of agar.  In one dish, we tested two disinfectants:  Lysol and Palmolive Antibacterial dishwashing detergent.  In the second dish, we tested two antiseptics:  Bactine and Triple Antibiotic Ointment.  I chose these antiseptics and disinfectants simply because I had them on hand.  You can use anything you have available.


The third dish was the control.  It was inoculated with soil bacteria, but received no further treatment.  We checked for "zones of inhibition" after 24 and 48 hours.  
Soil samples were used as a source of bacteria.  The bacteria living in the soil are less likely to be human pathogens.  Nonetheless, if you do this lab, be sure to have the students securely tape up each dish after the dish has been inoculated with the soil sample and the antiseptic or disinfectant has been added.  After the bacteria have begun to grow, I do not allow the students to open the Petri dishes.


These photos show the results of the lab.  Dishes were incubated for just 24 hours at a temperature of 25 degrees Celsius.  An amazing amount of growth will occur in just 24 hours.  Descriptions of each dish are found below the photograph.

 

I used a hole punch to make filter paper disks.  The disks were then dipped into different solutions of antiseptics and disinfectants.  You can see the filter paper disk on each side of the Petri dish in the above photo.  In this dish, two disinfectants were tested.  The disinfectant on the right did an excellent job in inhibiting the growth of the bacteria.  Notice the large zone of inhibition around the filter paper disk.  This disinfectant was Palmolive Antibacterial dishwashing detergent.  The disinfectant used on the left was Lysol.  There is only a small zone of inhibition around the Lysol disk.

In this Petri dish two antiseptics were tested.  The filter paper disk on the right had the larger zone of inhibition.  This antiseptic was Bactine.  The antiseptic tested on the right was Triple Antibiotic Ointment.

This was the control dish.  The filter paper disks were dipped into distilled water only.  Notice that there is no zone of inhibition around either disk.

I hope that you will give this lab a try.  It is so much fun for students to grow bacteria.  Here is the link to this lab in my store on TeachersPayTeachers.com:

The Effects of Antiseptics and Disinfectants on Bacterial Growth