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

Lab: Microorganisms in the School Environment

How clean is your school??

We have just completed some bacteria labs in our Biology 1 classes.  The first lab we did is called "Microorganisms in the School Environment".  The students really like this one.  Each student is given a sterile Petri dish of nutrient agar and allowed to choose a location in the school.  The purpose of the activity is to determine where in the school the most bacteria are found.  Students take a sterile swab and rub along surfaces in their location, then streak their swab across the surface of their agar.  Dishes are incubated for 48 hours, and the total number of colonies are counted.  


Students are often amazed at the results.  The students are always convinced that the cafeteria and the bathrooms will be overrun with bacteria, but the results usually show that these locations have the fewest bacteria.  Almost always, we find that a locker has the highest number of bacteria!

I don't place a lot of validity on the test results, but it is a fun activity to do when teaching a unit on microorganisms.   Just remember to have the students seal their dishes with tape, and do not allow the dishes to be opened after the bacterial colonies have grown.


Here is the link to my lab on TeachersPayTeachers.com as well as links to some related products.


Lab:  Microorganisms in the School 
Environment

Viruses and Bacteria Complete Unit Plan

Bacteria Homework / Study Guide

Happy Teaching!!

AP Biology Exam: It's Never Too Early to Start Reviewing

Click picture to download PowerPoint.

The key to success is REVIEWING!!

If you have taught AP (Advanced Placement) Biology, then you know that the amount of material that must be covered before the exam is daunting.  I have had great success with my AP exam scores.  I normally have between 60 to 80 students take the exam each year.  For the 2011 exam, I had 65 students sit for the exam, and we had an average score of 4.3.  Admittedly, this is one of the best years I have ever had.  It was a great group of students who were highly motivated.

I am convinced that the key to success is how you review the material with your students.  I begin to review with my students on February 1.  I am fortunate to have a 70 minute class each day.  I give a prayer of thanks for this each and every day, and I realize that most AP teachers do not have this luxury.  Beginning on February 1, I use the first 10 to 15 minutes of class to review a topic that we have previously covered earlier in the school year.  The remaining class time is used to cover new material.  The day before the AP exam in May, I am still reviewing and still covering new material!!

We have to convince our students that they must review, review, review before the exam.  I have written a set of powerpoints that I use for review. These are not teaching powerpoints.  These are just slide after slide of question and answer.  The students are not going to remember every little detail, so I try to make sure that they are solid on the basic facts.

Here is one of my review PowerPoints that I hope you will download.  It covers the characteristics of carbon and the organic compounds.

AP Review: Carbon and Organic Compounds ---- It's FREE!!  I hope you find this useful for your classroom.

Happy Teaching!

Paper Chromatography Explained: Diagram, Lab Ideas, and Classroom Tips

Looking for a low-prep, high-impact paper chromatography experiment to spark curiosity in your middle or high school science classroom? Paper chromatography is a classic lab technique that allows students to separate and analyze mixtures through hands-on investigation. In this paper chromatography experiment, students observe how different substances move along chromatography paper at different rates, and a simple diagram helps illustrate how solubility, polarity, and molecular properties affect separation. Whether you are introducing the scientific method, studying photosynthesis, or exploring real-world applications of chemistry and biology, paper chromatography is a versatile and visually rewarding lab to include in your curriculum.

What Is Paper Chromatography?

Paper chromatography is a simple chromatography technique used to separate the components of a mixture. This method works by taking advantage of differences in solubility and molecular interactions, allowing substances to be identified based on how far they travel up a strip of paper in the presence of a solvent. In the real world, chromatography is an essential analytical tool used in fields such as forensics, toxicology, and pharmacology. Police labs use chromatography to detect drugs and toxins in blood and urine samples, making this paper chromatography lab a meaningful way to connect classroom science to real-world STEM careers.

If you are looking for a ready-to-use paper chromatography lab for your classroom, you can find the complete student instructions, data tables, and teacher notes in my Paper Chromatography Lab resource on Teachers Pay Teachers.

Paper Chromatography Diagrams

These paper chromatography diagrams show how a solvent moves up the chromatography paper, carrying dissolved substances with it. Different components of the mixture travel at different rates based on their solubility and attraction to the paper, resulting in visible separation. This visual helps students better understand how paper chromatography works during the experiment. 

Paper Chromatography Experiment Overview

👉 The process is straightforward but packed with learning potential. A small dot or line of a sample (like ink or plant pigment) is placed near the bottom of a strip of chromatography paper. This strip is then placed vertically into a container with a shallow layer of solvent. As the solvent travels up the paper by capillary action, it carries the components of the mixture with it.

Here’s why the mixture separates:

• Solubility: More soluble substances dissolve better in the solvent and move farther up the paper.
• Molecular Weight: Smaller molecules tend to move more quickly than larger ones.
• Polarity: The cellulose in the paper is polar. More polar substances stick to the paper and don’t travel as far, while non-polar substances move more freely.

Chromatography Lab Ideas for the Biology or Physical Science Classroom

💧 Ink Separation

A fun and accessible introduction to chromatography is separating black ink from markers. Many black inks are actually mixtures of several colors. When placed in water, water-soluble inks spread apart into bands of dye. Not all markers will work the same way. Permanent inks may require rubbing alcohol or another solvent to separate. This gives students the opportunity to test variables and compare results across different solvents and ink types.

🍃 Plant Pigment Separation

This is a favorite in high school biology, especially during units on photosynthesis or plant biology. Students can extract pigments from leaves and discover that the color they see is actually a mix of chlorophyll-a, chlorophyll-b, xanthophyll, and carotene.

Fall is a perfect time to collect a variety of leaves from trees around your school. But if you’re teaching in winter, spinach leaves from the grocery store work just as well.

Materials for a Paper Chromatography Experiment

You don’t need a fancy setup to get started. Here's a basic chromatography kit:

• Chromatography paper (filter paper or coffee filters can work in a pinch)
• Small containers (test tubes, jars, or beakers)
• Solvents (water, rubbing alcohol, acetone, or other safe household solvents)
• Samples to test (leaves, markers, food dyes, etc.)
• Pencils, rulers, and scissors

Tip for teachers: Always test your materials and solvents in advance. Be sure to follow proper lab safety protocols, especially if using alcohols or other flammable substances.

Paper Chromatography Lab for High School Biology and Chemistry

Paper chromatography is one of the most effective chromatography labs for high school biology and chemistry classes because it allows students to visualize molecular differences directly. This chromatography experiment helps students understand key concepts such as polarity, solubility, intermolecular forces, and molecular structure.

In high school biology, paper chromatography is commonly used to separate plant pigments during photosynthesis labs. In chemistry classes, students use chromatography to analyze ink, food dyes, and other mixtures. Because the setup is simple and inexpensive, this chromatography lab is ideal for introducing experimental design, controlled variables, and data analysis.

This paper chromatography lab also helps students connect abstract molecular concepts to real, visible results, making it one of the most memorable chromatography activities in the science classroom.

What Solvent Should You Use?

The answer depends on the solubility of your sample. Water works well for many inks and food dyes. For permanent markers or plant pigments, isopropyl alcohol or acetone may be more effective.

Pro Tip: Encourage students to design their own investigations. They can test multiple solvents on the same type of ink or compare different brands of markers to determine which separates most clearly.

Why Use Paper Chromatography in the Biology Lab?

Paper chromatography gives students hands-on experience with:

• Designing and conducting controlled experiments
• Observing molecular behavior and physical properties
• Making qualitative and quantitative observations
• Connecting lab techniques to real-world applications

It’s also a visually exciting lab. Watching vivid colors separate into bands on a strip of paper never gets old, and makes for excellent lab notebook sketches!

Check out this post on my blog, Leaf Pigment Chromatography, for additional photos and information. 

You may also be interested in my osmosis lab using dialysis tubing and my potato osmosis experiment, which help students understand diffusion, osmosis, and molecular transport in cells. Check out these blog posts:

• Potato Osmosis Experiment
• Osmosis Lab Using Dialysis Tubing

Frequently Asked Questions About Paper Chromatography

What is chromatography used for?
Chromatography is used to separate and analyze mixtures by observing how different substances move through a medium. Scientists use chromatography in fields such as forensics, medicine, environmental science, and food testing.

Why does paper chromatography work?
Paper chromatography works because different substances have different attractions to the paper and the solvent. These differences cause components of a mixture to travel at different speeds, resulting in separation.

What can students learn from a paper chromatography experiment?
Students learn key lab skills such as experimental design, data collection, observation, and analysis while exploring concepts like solubility, polarity, and molecular interactions.

How do you perform a paper chromatography lab in the classroom?

To perform a paper chromatography lab, students place a small sample of ink or plant pigment near the bottom of chromatography paper and suspend the paper in a solvent. As the solvent travels upward, it separates the mixture into its components based on solubility and polarity. Students can measure how far each component travels and calculate Rf values to analyze the results and compare substances.

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• paper chromatography lab procedure

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Ready to Try This With Your Students?

These chromatography labs have been classroom tested and include complete student instructions, answer keys, and teacher guidance for easy implementation. If you're looking for classroom-ready chromatography labs, I have two student-tested resources that include everything you need: detailed procedures, printable lab handouts, answer keys, and grading rubrics.

🔬 Matter Lab Stations: Ink Separation – Perfect for introducing lab skills and the scientific method in both middle and high school.

🌿 Plant Pigment Chromatography Lab – Ideal for exploring photosynthesis and leaf pigments in your high school biology class.

Both labs are designed to save you prep time while providing meaningful, standards-based instruction. You can find them in my Teachers Pay Teachers store.