Category Archives: Nature of Science

Image Histogram Analysis

Note: This experiment is being postponed and will be re-visited after Spring Break.  Timelines and deadlines will be revised soon.  Thank you for your patience as we await guidance from our school district.  

Image Histogram Analysis

Background: You are excited for Spring and want to give your seeds a jump-start indoors to protect them from the cold.  You will transplant the seedlings into your garden when the weather warms up.  As a scientist, you are interested in keeping track of how fast the seedlings are growing so you can improve your process next year. One way to track plant growth is through image analysis.  Pictures can provide both qualitative data and quantitative data.  When pictures are subjected to histogram analysis, individual pixels are defined quantitatively and those data points can be plotted onto a graph to form a histogram.  New to histograms?  Learn more here.  New to histograms as they relate to photography?  Learn more here.

Materials: Paper pulp egg cartons, potting soil, and seeds.  Together, these will form the “incubator garden.”  Also, digital camera and image analysis software capable of generating image histograms.  I will be using the Image Histogram Creator available for free online by Sisek because it is simple to use and allows histogram data to be exported to a spreadsheet program like Microsoft Excel or Google Sheets.

Challenge: Evaluate and record the growth of seedlings by taking daily photographs of the incubator garden and tracking changes in luminosity and color.  Beginning on the day seeds are planted, take daily pictures and minimize as much picture variability as possible by keeping the lighting and camera distance consistent.  **Note: This is really important and will probably be the hardest part of the experiment!  The solution you engineer to minimizing variability in light and distance should be carefully documented in your lab report.

Deadline: Create a Google Doc titled “Egg Carton Garden – Your Name” and share it with Mr. Swart.  Write the Purpose and Procedure sections.  First drafts must be shared no later than Wednesday, April 1.  Students are encouraged to create their own gardens.  However, students are welcome to use the images posted to this page and conduct image analyses with those.  You will be responsible for completing the Results and Conclusion sections of your Google Doc.  When you are finished, your lab report grade for this document will replace your lowest lab report score from 2nd semester.  Lab reports will be due Friday, May 1.

Data Collection: Between April 3 and April 24, pictures will be taken and posted to this page.

Disclaimer: In the event school does not reopen on Monday, April 27, Mr. Swart reserves the right to extend deadlines and data collection so we can learn as much as possible from this experiment.

Experimental Design Challenge

Note: This experiment is being postponed and will be re-visited after Spring Break.  Timelines and deadlines will be revised soon.  Thank you for your patience as we await guidance from our school district.  

Experimental Design Challenge!

Background: You have a Red Tip Photinia tree in your yard that needs to be removed.  It’s growing too close to your house and you are concerned about foundation damage if it gets any bigger.  Inspired by Groot, you decide to propagate the plant by taking cuttings and planting them in a new location.  Now comes the hard part: what to do?

Observations: The plant is currently growing like crazy because Spring has arrived.  The part of each branch closes to the trunk has a woody stem, while the new branch growth stem is red in color.

Materials: You intend to plant the cuttings directly into the soil in your yard.  The best available section of your yard to conduct the experiment is along the western fence line.  You also bought rooting hormone powder and want to determine: 1) will it promote root growth as advertised and 2) will using it result in healthier new plants?

Challenge: Design an experiment to determine the best way to propagate the plant.

Deadline: Create a Google Doc titled “Will It Grow – Your Name” and share it with Mr. Swart.  Write the Purpose and Procedure sections.  First drafts must be shared no later than Wednesday, March 25.  The experiment will begin Friday, March 27 and will end Friday, April 24.  You will be responsible for completing the Results and Conclusion sections of your Google Doc.  When you are finished, your lab report grade for this document will replace your lowest lab report score from 2nd semester.  Lab reports will be due Friday, May 1.

Data Collection: Between March 27 and April 24, data will be collected and posted to this page.

Disclaimer: In the event school does not reopen on Monday, April 27, Mr. Swart reserves the right to extend deadlines and data collection so we can learn as much as possible from this experiment.

 

Sleep

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?

Conclusion Writing

Reminder: Lab reports (one Google Doc per team shared with Mr. Swart), and the Plants Notes organizer (one per person) are both due Friday (May 25).  

Having acquired a deeper understanding of plant biology, we set our sights on the final piece of the Baggie Garden lab report: the Discussion / Conclusion section.  Remember, lab reports are organized into at least four parts in the following order:

  • Introduction (minimum of one paragraph)
    • State the scientific concept the lab is about.
    • Describe what you know about germination and how the lab is investigating the process of germination.  Include a discussion about how the energy used for germination is different from the energy used for plant growth.
    • State the hypothesis in if/then/because format for the experiment and then explain:
      • why this particular hypothesis was selected
      • how the experiment will add to your understanding of germination
  • Procedure:
    • Consists of a numbered list of steps
    • Each step includes one action
    • Must be detailed enough (including materials used) that someone unfamiliar with the lab could exactly repeat the experiment
  • Results
  • Discussion / Conclusion
    • Connect experimental results with Hypothesis.  Explain how the experimental design enabled you to test your hypothesis.
    • Explain how each manipulated variable affected the responding variable(s).  Be as specific as possible when describing the changes observed.  For example, as light intensity decreased from 200 lux to 40 lux (a decrease of 160 lux), the number of seeds germinating decreased from 80% to 40% (a decrease of 40%).
    • Explain how the data support your conclusion.  Regardless of whether your hypothesis was correct or incorrect, you now have data to help you better understand how the variable you selected impacts germination.  Explain that connection as thoroughly as possible.  By now, you may have read additional information about seed germination which may help you explain your results.  Include as much supporting evidence as possible from the sources you have examined.  If your results contradict what is published, explain how your results are different.  Provide a scientific explanation for the trend you observe in your data.
    • Provide a minimum of three possible sources of experimental error.  Explain how each possible source of error might influence the results your results.
    • Provide one opportunity to improve the experiment.  If you were to repeat this experiment, what would you do differently, and why?  Scientists work carefully and methodically, with experiments building on each other.  Think of your next experiment as the next step beyond your current experiment.

Seed Germination and Cellular Respiration

With our seed germination experiment coming to a close yesterday, students are taking a break from writing the lab report in order to add to their knowledge about plants. We began with a Crash Course video about vascular plants:

Next, each student was assigned to read pages 758-763 from the textbook Biology (Raven & Johnson, 4th Edition, 1996).  Students recorded definitions to vocabulary words and summarized sections using the Plants Notes organizer.  The organizer is due Friday, along with the Lab Report, and should help students improve Introduction sections and help support their writing of the Conclusion section later this week.

Data Analysis and Graphing

Today marks the final official day of data collection.  After collecting and recording Day 6 observations, students should complete their data table tracking how many of their seeds germinated.  Next, students should construct a data table showing how many seeds germinated as a percent of total seeds (per condition).  Finally, a graph of the percent germinated data needs to be made.  Both data tables and the graph need to be transferred to the Results section of the lab report.

The Results section should include a written explanation of what the data tables show.  Explain how each experimental condition affected seed germination, using the control bag of seeds as the comparison group.

Lab Report Checklist (how to know when you are done…for now)

  1. Introduction
  2. Procedure
  3. Results
    • Data Table #1 = # of seeds germinated
    • Data Table #2 = % of seeds germinated
    • Graph of Data Table #2
    • Explanation of what graph are (not what they mean)

Data Collection and Measurements

With the first week of our experiment coming to a close, students should return Monday with the following sections of their lab reports completed:

  • Introduction – at least one paragraph, perhaps two, filled with information about germination (hook your reader!) and explaining why you selected your manipulated variable.
  • Procedure – detailed enough that a stranger could repeat exactly what you did!
  • Results with Data Table – create the data table in Google Sheets.  Keep track of the number of seeds that germinate each day.  Then use your data to calculate the percent of seeds that have germinated.  You will create a graph of the percent germinated data next week.  Additional data collected will improve your report and result in an improved lab report score.

All team members must participate equally to writing the lab report.  Pictures are a great way to show your reader both your procedure and your results.  Pictures can go in the Results section and should be clearly labeled and organized.

Introduction Writing

In addition to efficiently observing seed germination, making measurements of roots and shoots, and recording all the data in Google Sheets, students should browse through the following resources:

Students should note whether the seeds used in their own experiment are dicots or monocots, and be prepared to explain the difference between the two.  Students should take careful notes about the optimal conditions for seed germination, focusing on the biology of the seed and especially the sources of energy the seed uses to germinate.

Next, students should work together to write the Introduction paragraph of their lab report.  The Introduction should include the following:

  • State (in a sentence or two) the scientific concept the lab is about.  Hint: germination!
  • Describe what you know about germination and how the lab is investigating the process of germination.  Include a discussion about how the energy used for germination is different from the energy used for plant growth.
  • State the hypothesis in if/then/because format for the experiment and then explain:
    • why this particular hypothesis was selected
    • how the experiment will add to your understanding of germination

Observations and Data Table

Today, we focused on identifying the experimental data to include in the Results section of the Baggie Garden Experiment lab report.  We compared the pros and cons of collecting lots of data with collecting a focused amount of data.  Students identified, discussed, and justified which experimental endpoints they wanted to collect for their experiment, and then created data tables in their lab notebooks to collect the data.  Finally, students made their first careful observations of their baggie gardens and recorded their observations.  We discussed how to calculate percentages so students can track the percent of their seeds that have germinated (notes below):

IMG_1839

Finally, students were shown an example spreadsheet created in Google Sheets.  The table below can be copied into Sheets and modified as needed:

Day 0 Day 1 Day 2 Day 3 Day 6
Control
Experimental Condition 1
Experimental Condition 2
Experimental Condition 3

The slide deck includes lesson content, including a link to the Chia Pet video which is also available below.

Setting up the Garden

Students established their Baggie Garden experiments today, setting up their experiment bags and one or more experimental control bags.  We began class with a brief overview of the day, and then students worked in groups to write a detailed experimental procedure.  Once their procedure was reviewed and teacher-approved, the students assembled their baggie gardens, using the resources available to test their hypotheses.

For groups testing temperature as their manipulated variable:

  • Freezer -10C
  • Refrigerator 9C
  • Room 23C
  • Warm box 30C

Tomorrow we will make our first experimental observations and then discuss how to organize how to collect and organize data relevant to each group’s research question.