Today we learned about the three major cell types: prokaryotes, eukaryotes, and archaea. The PowerPoint included detailed notes on the similarities and differences of the cell types, and concluded with a SciShow video about the tardigrade. Students then had time to read through the extremophiles reading packet which is due Wednesday.
As a reminder, we will meet in our classroom at the beginning of the class period, after which we will head down to the library for a meeting with Christine Froschl, Outreach and Volunteer Coordinator at the Environmental Science Center at Seahurst Park. Ms. Froschl will be speaking to us about the ESC and will prepare us for our upcoming field trip to Seahurst Park.
Today we focused on 8 factors that are commonly found in environments we consider to be extreme. Students began the lesson with an introduction to the bell curve and an brief explanation of the mean and standard deviation. Students then silently brainstormed three examples of things they consider extreme, with an explanation about why. During our share out, students were encouraged to consider whether the idea of “extreme” is relative. For example, we might regard a skydiver as someone who participates in an extreme sport. However, the skydiver might share a different perspective. Similarly, we might classify a polar bear as an extremophile, given it’s ability to live in extremely cold temperatures. However, the polar bear, being unable to live comfortably away from the south pole, might consider organisms living in warmer climates as extremophiles. After learning about the 8 factors and exploring representative locations and organisms at those locations (see Power Point slides), students completed their extreme environments critter diagrams from yesterday.
At the beginning of class yesterday, students were faced with the following scenario: You are an extreme environment engineer. Pick your next work assignment. The options were: The Ocean Floor, Olympus Mons (tallest known volcano in the solar system, located on Mars), Antarctica, and The Moon. Today, students were grouped based on their work site preference. Working in groups of 3 or 4, students then were assigned the extremophiles reading packet. Each group member was assigned a roles (slide 1), with the role rotating after each paragraph was read. The roles were: Reader, Paraphraser #1, Paraphraser #2, and Recorder. The Reader was responsible for reading the paragraph out loud to the group. The Recorder highlighted words that were challenging for the Reader or needed to be defined for comprehension. Paraphraser #1 was responsible for paraphrasing the main ideas they heard from the Reader. Paraphraser #2 paraphrased what they heard from Paraphraser #1, further distilling the key points down to a single sentence or two. Ultimately, those main points served as discussion points for answering the questions on the worksheet. The exercise served many learning purposes. Students practiced reading challenging scientific words and were supported by their group members who might be more familiar with the word or who could help the group find out the correct pronunciation and meaning. Students also practiced listening and paraphrasing, applying those skills to answer specific comprehension questions about extremophiles. Many students were able to complete the reading and turn it in at the end of class. Students needing extra time should complete the worksheet as homework and turn it in at the beginning of class tomorrow. At the end of the class period, students drew critter diagrams (slide 2) in their lab notebooks and filled out the leg corresponding to their chosen extreme environment. The legs represent extreme conditions encountered by life either currently living, or wishing to live, in the group’s extreme environment. Groups will share out their legs of the critter diagram tomorrow.
We began the day with a quick video about the tardigrade (below). Then, students took their second clicker quiz of the year today. Questions included a review of the metric system, tools scientists use, ecosystem vocabulary, and a question about extremophiles. Have a safe and fun Homecoming!
In lesson 10, we continued with our study of osmosis, focusing on the extreme environment of the Great Salt Lake. Students learned that a railroad causeway was built across the lake more than 60 years ago, physically separating the lake into two sides. Only the south side of the lake receives a continuous supply of freshwater, causing the salinity of the south side to be much lower than the north side. As a result, the ecosystem of the south side of the lake is much more robust than the north side which is inhabited primarily be halobacteria. Considered extremophiles because of their unique ability to live in extremely salty water, halobacteria are present in such abundance that they color the water in the north side of the lake purple (because of the rhodopsin protein they produce). As evidence of their learning, students completed a case study worksheet and hypothesized what might happen to the existing Great Salt Lake ecosystem if the causeway were removed.
In lesson 9, our first lesson of the week, we circled back to osmosis, a concept students learned about early in the school year. We connected the theme of “Water Follows Salt” with the reality that cell membranes contain pores and channels that regulate the flow of everything across the cell membrane. We discussed the vocabulary of osmosis in the context of blood, recognizing that blood cells in plasma (isotonic) behave much differently than blood cells in water (hypotonic) or in saltwater (hypertonic). We then thought about how salmon might be able to transition from freshwater to saltwater during their life cycle. By connecting pore protein expression (via the Central Dogma) with evolution, students now have the foundation necessary to explain how salmon can hatch from an egg fertilized in a freshwater stream, migrate through the brackish waters of an estuary out into the Puget Sound, travel for years in the salty Pacific Ocean, and eventually find their way back to the steam from which they were born to complete their life cycle. We wrapped up with a video about ice cave exploration, in which the concept of extremophiles was presented. Students then transitioned to Work Time where they read an article and answered questions about extremophiles.