Category Archives: Homeostasis


Ever wonder why humans spend 1/3 of our lives sleeping?  Watch the PBS NOVA episode Mysteries of Sleep and learn the answer to that question and more!

Learn more about the connection between adenosine, caffeine, and sleep by watching the TedEd video below:


Turn it up to 11!

  • Create a sleep journal.  Think about the factors that might impact your sleep each day, then track those along with how much sleep you get each night.  Which factors seem to affect your sleep?  Which factors don’t seem affect your sleep?  Add and remove factors to help you dial in on how to get the best possible sleep each night.
  • Create a dream diary.  Record your dreams upon waking.  Write them down, draw them out, or narrate them into your phone.  Notice any trends or patterns?  How often are you able to recall your dreams?  Does your ability to remember your dreams correlate with how long or how well you sleep?  Does the content of your dreams correlate with your past, present, or future experiences?  Do you have recurring dreams?
  • Learning to remember. Feeling tired after a long day of learning at school?  Try a Power Nap and see whether it helps you remember what you learned during the day.  Are you more efficient at completing homework before or after a Power Nap?

Week 3

Week 3: September 16-20

Monday, September 16 (LS1-2): After making and recording corn seed observations, students plant seeds in soil in preparation for the next phase of our experiment.


Next, students will discuss the analysis questions from last Friday’s assignment.  In The Breath of Life reading, students learned how the respiratory system of humans enables gas exchange, with the lungs inhaling oxygen and exhaling carbon dioxide.  The gas exchange occurs within the alveoli, thin-walled sacs inside the lungs.  The reading introduced the concept of feedback systems, focusing on the special nerve cells in the cardiovascular and nervous systems that can sense changes in pH.  As carbon dioxide builds up, the blood becomes more acidic, and the lungs are forced to exhale to rid the body of carbon dioxide which then brings the pH back to normal levels.



For the last few minutes of class, we made a list of some of the ingredients found in tacos, and then categorized those food items as carbohydrates, proteins, or fats.  We will dig into this work much more deeply tomorrow.


Tuesday, September 17 (LS1-2):  After making and recording corn plant observations, students actively took notes and shared their understanding of biomolecules.  Glucose is a simple sugar and the key ingredient in cellular respiration, the process organisms use to generate vast amounts of ATP energy.  Sugars are one type of biomolecule.  Our work today was to learn about three major classes of biomolecules: proteins, fats (lipids), and sugars (carbohydrates).  We reviewed the monomers and polymers of each, and then students read pages 328-332 in our textbook and completed the associated worksheet.  The assigned reading is titled Food: Our Body’s Source of Energy and Structural Materials.  Now that students understand the link between photosynthesis (chemical potential energy stored in glucose), cellular respiration (glucose metabolized to transfer the energy in glucose to ATP), and the larger connection with the respiratory and cardiovascular systems, it is time to learn more about how the digestive system makes use of the variety of foods available to us.  It is time to think beyond glucose.

Notes from class:




Wednesday, September 18 (LS1-2): After making and recording corn plant observations, we reviewed the reading from yesterday and focused in on an important group of enzymes responsible for digestion in the human digestive system.  For the remainder of class, students worked with a partner on the Digestive System Gizmo activity packet.

Thursday, September 19 (LS1-2): After making and recording corn plant observations for the final time, students will work with a partner to complete the Digestive System Gizmo activity packet.

Friday, September 20: Students had the entire short Friday class period to work on the Digestive System Gizmo activity packet.  Students were instructed to complete, at a minimum, through Activity B as homework before class on Monday.

Keep Learning!

Watch The Digestive System video by Mr. Anderson at Bozeman Science to learn more about this important area of study!

Week 1

Week 1: September 4-6

Wednesday, September 4: Networking 

To kick off the school year, students will meet the teacher, learn about our classroom, and then complete the Ten Facts About Me survey.  The information they share will help introduce the students to each other and the teacher.  Students will share information about themselves with each other, constructing a network diagram during the process.  The survey and network diagram will be turned in at the end of class.

Thursday, September 5: Human Homeostasis (HS-LS1-3)

Computers are an invaluable tool for modern-day biologists.  We will rely on computer technology frequently this school year as a means to acquire and share knowledge.  For this lesson, students will work with their assigned partner to create free accounts at  We will periodically utilize the simulations (called Gizmos) on the website.  After both partners have successfully created accounts, students will work together with the assignment of completing Activity A of the Human Homeostasis Gizmo worksheet.  Note: students faced a number of challenges today while working on the Gizmo (too few functioning computers and several student gmail accounts locked) so the Gizmo will not be counted as an assignment.

Friday, September 6: Human Homeostasis (HS-LS1-3)

When class begins, students will review important vocabulary concepts from yesterday’s work with Mr. Peterson.  Next, students will be introduced to our class experiment.  Students will monitor their heart rate and respiration rate (one minute each) on at least three separate occasions today (Friday), tomorrow (Saturday), and Sunday.  Each day, students should record resting rates, rates after light activity, and rates after exercising.  Students will record each data point on this Google Form and we will analyze the class set of data next week.  Finally, students received copies of the class syllabus and safety contract.  Students will read and return both copies on Monday, signed by both the student and a parent or guardian.

Keep Learning!

For students interested in pushing their learning beyond the content learned in class, we can look to the Next Generation Science Standards (NGSS) for High School Life Science (HS-LS) for the standards we are investigating and look for assessment boundaries.  The assessment boundary for HS-LS1-3 states: Assessment does not include the cellular processes involved in the feedback mechanism.  This means the WCAS exam students take at the end of their 11th grade year (based on understanding of the NGSS) will include questions that approach the assessment boundary but do not include content at that boundary.  Therefore, students looking to learn at an advanced level should explore content at or beyond the assessment boundary!  The Keep Learning! section located at the end of each week’s post is a great place to get started.  For this week, check out the videos below focusing on  Homeostasis and Negative/Positive Feedback:

Unit 1 Wrap-up

To conclude Unit 1, students received back Day 2 of the exam and we graded it together as a class.  Students then received Day 1 of the exam (already teacher-graded) and a Unit 1 Exam Reflection worksheet.

Next, students conducted a peer review of another student’s Egg Lab report and provided feedback using the Egg Lab Report Peer Review Form.  Students used the remainder of the class period to revise their own lab reports using the feedback received.  All Egg Lab reports are due no later than Wednesday, November 1.  Students may submit a paper copy, email a copy, or ideally share a copy using the “Share” button in Google Docs.

Unit 1 Review

Our work in Unit 1 came to a close today with students working as a class to explain why Lena Bedolla died after taking Ecstasy.  We filled out the Blood-Brain Barrier worksheet to help explain what happened to Lena as a result of her consuming Ecstasy and drinking a lot of water.  A copy of our work is shown below:

Students had the remainder of the class period to complete their Egg Lab reports (due by midnight Friday) and to prepare one page of notes that can be used on the Unit 1 Exam tomorrow and Friday.

Egg Lab Report – Day 2

Step 1: Read this post all the way to the end!

Instructions for the Introduction, Procedure, and some of the Results section (creating a data table) are included in last Friday’s post (October 20).  For today, students should complete the Results section by calculating the average of each egg solution group.  For example, add up all of the change in mass values for the eggs that were in corn syrup, then divide by the number of eggs that were in corn syrup.  Repeat for all of the solutions.  Remember, the more data you include, the more “real” your results will be.  Please consider adding data from one or more additional class periods!  All of the data from my three biology classes can be found on last Thursday’s post (October 19).

Next, write the Discussion section.  In the Discussion paragraph, discuss what you think your results mean.  Do they make sense given what you know about osmosis (think about a cell – the egg – in isotonic, hypotonic, and hypertonic solutions).  Explain your thinking!  Explain why you think the egg changed mass in the different solutions.  What evidence do you have for the movement of water across the cell membrane?  Why do you think some of the eggs gained or lost more or less mass (why were the results variable)?  How can we use the word “homeostasis” to describe how the egg changed mass when placed in a different environment?  What are three possible sources of error that could have affected the results?  What would you change to improve the experiment next time?  All of these questions should be addressed in the Discussion section.  You may need to write more than one paragraph to clearly explain your thinking.

In the Conclusion section, write a paragraph explaining both what happened in the experiment and how it connects with the research you have done into Lena Bedolla and her death from Ecstasy.  How can you use the evidence to help explain what happened to Lena?  You should be able to explain how Ecstasy changed the way Lena’s urinary (excretory) system worked, affecting her cardiovascular system and her nervous system, and ultimately leading to her death.  Your Conclusion section should clearly explain how the Egg Lab provides evidence to support your understanding of why Lena died.

Finally, if you used any outside resources (other websites) to help you with this lab report, list them in the References section.  If you didn’t use any, you do not have to include a References section.

This lab report is due tomorrow at the end of the class period.  If you think you will need additional time, work on it tonight as homework.

Egg Lab Report – Day 1


  • What did we do?
  • Why did we do it?  
  • What were we observing?  
  • What were we learning about?

Procedure – should be in your lab notebook and on class website

  1. Step 1
  2. Step 2
  3. Continue until finished


Data table of class data (Table > Insert table > select number of columns and rows

Calculate average values for solution groups

Graph the averages (use Google Sheets)




Egg Lab Day 4 / Class Results

The egg lab concluded with students receiving the following instructions:

  1. Gently rinse and dry egg
  2. Measure and record the final mass
  3. Discard the egg and cup
  4. Calculate the change in mass of the egg

To calculate the change in mass, students were instructed to subtract the initial mass (measured yesterday) from the final mass (measured today).  A positive change means the egg gained mass.  A negative change means the egg lost mass.  Students reported out their data (shown below), and then we discussed the movement of water across the membrane of eggs placed in various solutions (final picture below).

Period 1 Class Data
Period 4 Class Data
Period 6 Class Data
Membrane Movement

Egg Lab Day 3 / Catch-up Day

For day 3 of the Egg Lab, students worked with their lab groups to complete the following:

  1. Gently rinse each egg to remove any last parts of the shell.
  2. Gently dry each egg.
  3. Measure the mass of each egg separately (in grams) using the balance.
  4. Each student in the group should record the mass of each egg in their lab notebook.  A group of four students will each have four egg mass recordings in each lab notebook.
  5. Rinse out the cup and carefully dry it, being careful to make sure note which egg went with which cup.  This matters!  The cups are labeled with student names, and we need to keep track of the mass of each egg, so we need to know which egg belongs to which student.
  6. Return the egg to the correct cup.
  7. Carefully cover the egg with one of the following:
    • Vinegar (egg #1)
    • Corn syrup (egg #2)
    • Distilled water (egg #3)
    • Bonus liquid (egg #4)
  8. Cover the cup with plastic.
  9. Record any additional observations about the egg during the class period.
  10. Return the cup to the counter for further observation tomorrow.

For the remainder of the class period, students should work hard to complete missing biology assignments.  We have an exam next Thursday, so students who are caught up on work, including last night’s homework, should begin assembling a page of notes to use on the exam.

For tonight’s homework, watch the video below and take notes!  The video will reinforce the learning from October 12 (Membrane Movement lesson).

Cell Membranes

After a week of re-learning cell organelles and observing cells under the microscope, today students learned about how the cell membrane works.  The primary focus of the lesson was to provide students with the vocabulary to explain the concepts of osmosis and transport of water across the membrane via the membrane protein channel aquaporin.  Students should review the Membrane Functions PowerPoint slide deck and commit the vocabulary terms to memory.  The aquaporin claymation video included in the slide deck is also provided below for easy access: