The Effects of Acid Rain on the Germination of Seeds

A few weeks ago, students were presented with an imaginary scenario:  they are scientists at a research laboratory, and have been contracted by a local town council to do some investigating.  A company is hoping to build a factory in the town (Rocketville), however a local farmer is concerned that pollution from the factory could lead to acid rain, which would have a negative impact on the growth of her crops.  The town council needs to decide whether to allow the factory to be built- it would benefit the town by bringing in jobs and revenue, but what about potential environmental impacts?  Specifically, students were tasked with investigating the impact of acid rain on the germination of vegetable seeds, since this was the concern the farmer in the scenario raised with the town council.  Students worked in small groups to plan an investigation, set up and carry out the investigation, write a lab paper detailing the results, and make a suggestion to the town council of Rocketville about whether they should allow the factory to be built in their town.

The first work that students did within their groups was to plan the investigation.  As a group, they came up with a question, did background research into the causes and effects of acid rain, developed a hypothesis, and planned an experiment to test the hypothesis.  The next step was to carry out the experiment.  While all groups were doing a similar investigation, each group decided the specifics of how they wanted to carry out the experiment.  Available to students were bean seeds, containers for their seeds, water, vinegar (to simulate acid rain), pH testing strips, and any other materials they thought they would need.  Each student group determined how many experimental seed groups to test, how many bean seeds to put in each group, and how to set the bean seeds up to encourage germination.  The experiment was carried out over a week, from Monday to Monday, with students checking seeds each day and adding water/acid to them as necessary.

Students set up groups of seeds with varying levels of acid to test the effect of the acid on seed germination.

Students note the difference in germination results between bean seeds given acid and bean seeds given water.

At the end of the experiment, it was time for students to look at their results, draw conclusions, and write a formal lab paper detailing the investigation.  Our classes spent two periods in the computer lab working on our papers.  Students were given directions about the various sections to include in their reports.  These included a summary (similar to an abstract), background (introduction), materials and methods, data, conclusion, and a section for a formal suggestion to the town of Rocketville about whether they should allow the factory to be built in their town.  Many groups included pictures of their seed specimens in the data sections of their papers, along with a data table.

Hard at work on lab reports!

As for the results, most groups came to the conclusion that acid rain has a negative effect on the ability of seeds to germinate.  In almost all groups, the seeds that received no acid did germinate, some more than others!  I don't think that any seeds that received acid germinated at all.  Because of this, most groups recommended that the town council not approve the construction of the factory- they felt that the acid rain that could come from the pollution of the factory would be too detrimental to plants. 

One group's results- left are seeds that received water only, right are seeds that received acid!

One group actually had a beanstalk begin to grow!

As the teacher, my goal for this activity is for the students to experience the scientific process from beginning to end, although we talked about how the end really isn't ever THE END in science!  Students are engaged because they can take ownership over the activity- they form a hypothesis, design the experiment, and carry it out.  Writing the paper allows them to analyze the results and form conclusions the way scientists must as they conduct research.  It takes a good bit of class time to design and carry out this experiment, not to mention write up the paper, but I feel the experience is well worth it for the students!

Current Events- Climate Change

During an earlier post, I discussed how I include an ongoing science current event assignment as part of my biology class, mainly because I feel it is important for students to realize how relevant science is to our world.  Many of the articles students have summarized so far this year deal with climate change- either directly or indirectly.  During today's discussion of current events in one of my classes, one article was specifically about climate change, another was about hotter than normal temperatures in the Arctic, another was about slow-moving hurricanes, and another was about large forest fires, such as those currently burning in the Amazon region of South America.  There was even an article about how climate change may have aided in the evolution of a deadly fungus, allowing it to adapt to human body temperatures and become more infectious to humans! Talk about a relevant issue that is obviously on students' minds!  I mentioned to my students that today a global climate protest took place in areas all around the world, inspired and led by young people, and we looked at some pictures of various protests around the world.  We discussed how the goal of the protests was to draw attention to climate change and to demand that those in positions of power in the world to work harder to take action on this issue.
Here is the link to the article we discussed:   Young People Lead Millions to Protest Global Inaction on Climate Change- NPR

Earthworms and Yeast and Beans, Oh My!

Much of our time this week was spent doing lab work, which is fun and exciting for just about everyone!  We continued to focus on identifying and describing characteristics that differentiate living organisms from non-living things, so we got up close and personal with some earthworms  to examine how they demonstrate characteristics such as internal organization, growth, reproduction, response to environment, and adaptations within the species.  Students seemed to enjoy watching the earthworms slither around on paper plates while they (students, not worms) made observations and did some research.


We learned about the different organ systems earthworms possess, including circulatory, nervous, reproductive, digestive, and muscular.  Students researched growth, reproduction, and adaptations of earthworms and observed how earthworms responded to stimuli such as light, touch, and water drops!

Students check for earthworm responses to various stimuli, including light and touch.

Later in the week we investigated a "mystery matter" to determine if the seemingly inanimate material was actually living.  Students set up test tubes of mystery matter with different amounts of food (sugar) and warm water.  They noted the smell, turbidity, frothiness, and balloon inflation at the beginning of the investigation and again after 24 hours had passed.  Many students were able to identify the mystery matter as yeast, but it was more difficult for them to determine whether or not the yeast was living- it just looks like little pellets of sand or rock!  

Students set up test tubes with "mystery matter," sugar, and water

We noted that the smell in the test tubes was much stronger after 24 hours and the balloons had inflated.  We eventually were able to reach the conclusion that the yeast was alive- it was using the chemical reactions of its metabolism to "eat" the sugar for energy and was producing carbon dioxide gas and alcohol as waste products.  Later in the year we will talk in more detail about this process of fermentation that yeast use to produce usable energy, so it will be nice to be able to reference back to observations that students made during this investigation.

Test tubes with balloons at the beginning of the investigation

Test tubes with balloons after several hours- balloons inflated due to carbon dioxide gas produced by the yeast.

To end the post I want to quickly mention another investigation that is happening in our classroom.  I will say more in a future post, but student groups spent last week designing an experiment to investigate the effects of acid rain on the germination of bean seeds.  This week they set the experiment up on Monday and have been checking the seeds each day throughout the week.  Next week students will make final conclusions and write a lab report based on their results! 

Stay tuned for more information about how our bean seeds responded to acid!

The First Few Weeks...

The first several weeks of school are always an interesting and busy time.  Starting the year off, I hope to give my students a really strong background about what science means and how it is done, and also what the branch of science called biology is all about.  We spent several days talking about the scientific process- about how science in the real world is not always like the "scientific method" steps we sometimes learn in school: question, hypothesis, experiment, conclusion- bam! done!  We talked about how the scientific process is more of a circular process- the stages of the scientific method are all there, but scientists may flow back and forth from one stage to another- the arrows showing the flow of the process don't just proceed in one direction, in other words!  We talked about some real life examples of how the scientific process has worked this way- from experiments about what caused a mass extinction, to those that determined that CFCs were destroying our ozone layer, to the discovery of DNA's structure.  

Following this, we are beginning the important task of trying to figure out just what "biology" is.  We now know that biology is defined as the study of life, but we are starting to realize that defining "life" isn't always so easily done!  It might be hard for some to accept, but maybe "life" or "living" is one of those terms that has a slightly different definition depending on who you ask to define it.  We developed a list of characteristics shared by living things, but realized that there are some times that this list may not be adequate to define what is living or not!

Biology students try to define life and categorize objects as living or non-living!

Another thing students have been hard at work on is learning a list of science-related prefixes and suffixes.  I hope that the knowledge of the definitions of these words will help throughout the year as students have to learn science vocabulary that sometimes seems like its own different language!  We started off with the word "pneumonoultramicroscopicsilicovolcanoconiosis," which may be a bit of an extreme example, but by breaking the word down into its smaller parts, we were able to get pretty close to its actual definition (a disease caused by the inhalation into the lungs of extremely small or fine volcanic silicon dust particles!).  Most of our biology vocabulary this year won't be quite that intimidating, fortunately, but hopefully knowledge of some short prefix/suffix words commonly used in science will make it a bit easier to figure out the terms we encounter this year.

Some of the science "mini-words," or prefixes/suffixes we are learning to facilitate our understanding of scientific vocabulary!