Day #5. Lesson plan
Students learn to apply the scientific method by formulating hypotheses, conducting experiments, observing results, and drawing conclusions. This structured approach to problem-solving is essential for developing critical thinking and analytical skills.
Objectives
- Students will understand the impact of ocean acidification on marine organisms through theoretical knowledge and hands-on experimentation.
- To observe and measure the effects of increased acidity on shells over a period of 4-5 class periods (we are on block schedule, 90 min. class time, every other day).
- To practice the steps of a controlled experiment, collect data, analyze it and to draw conclusions.
Vocabulary
- Hypothesis: an explanation of an observation that can be tested through experimentation
- Variable: a condition in an experiment that can be controlled or changed
Bellringer
- Bell ringer#5
- Alternative: Describe the difference between dependent and independent variable.
Lesson
How Ocean Acidification Affects Marine Organisms
- Start the day with Bell ringer#5
- Quiz
- Introduction (20 minutes)
- Topic Introduction: Briefly explain ocean acidification and its causes (increased CO2 emissions and the resulting absorption by oceans).
- Ocean acidification refers to the process by which the pH of seawater decreases, becoming more acidic. This occurs due to the increased absorption of carbon dioxide (CO2) from the atmosphere by the world’s oceans.
- Causes:
- Increased CO2 Emissions:
Human activities, such as burning fossil fuels (coal, oil, and natural gas), deforestation, and industrial processes, release large amounts of CO2 into the atmosphere.
Since the Industrial Revolution, CO2 levels have significantly increased, contributing to global climate change and ocean acidification. - Absorption by Oceans:
Oceans act as a major carbon sink, absorbing about 25-30% of the CO2 emitted into the atmosphere.
When CO2 dissolves in seawater, it reacts with water to form carbonic acid (H2CO3). - Chemical Reactions:
Carbonic acid dissociates into bicarbonate (HCO3-) and hydrogen ions (H+).
The increase in hydrogen ions lowers the pH of seawater, making it more acidic.
- Increased CO2 Emissions:
- Impact on Marine Life: Discuss how acidification affects marine organisms, particularly those with calcium carbonate shells or skeletons (e.g., mollusks, corals).
- The increased acidity affects marine organisms, especially those with calcium carbonate shells or skeletons, such as mollusks, corals, and some plankton species.
- Acidic conditions can weaken shells and skeletons, impair growth, and disrupt reproductive processes, threatening marine biodiversity and ecosystem stability.
- Topic Introduction: Briefly explain ocean acidification and its causes (increased CO2 emissions and the resulting absorption by oceans).
Here is a great video by Science Museum that explains ocean acidification.
- The Effect of Ocean Acidification on Marine Organisms – Lab
- Objective: Students will understand the impact of ocean acidification on marine organisms through theoretical knowledge and hands-on experimentation; To observe and measure the effects of increased acidity on shells over a period of 4-5 class periods.
- Safety Precautions: Students should wear safety goggles and gloves when handling vinegar and conducting the experiment.
- Procedure
- Hypothesis Formation: Have students form hypotheses about how increased acidity will affect marine organisms.
- Experiment Setup:
- Divide students into small groups (2-3 students/group).
- Each group should have two clear containers, seawater, vinegar, pH test kits, and shells.
- Students will label one container as “Control” and the other as “Experimental.”
- Fill both containers with an equal amount of seawater (e.g., we use 100 mL each).
- Instruct students to add a small amount of vinegar to one container (experimental group) to lower the pH, while leaving the other container as it is (control group).
- Add a small, measured amount of vinegar to the “Experimental” container to lower the pH. Start with 10 ml of vinegar and mix thoroughly. Measure and record the pH after adding vinegar. If the pH is not significantly different from the control (target pH around 7.5-7.8), add more vinegar in small increments (5 ml) until the desired pH level is reached.
- Add similar types and quantities of shells to each container.( We use one shell/container. Shells are similar in size and shape and are weighted before placing them in containers.
- Ensure the shells are fully submerged in the seawater.
- Perform a final pH measurement for both containers and record the values.
- Observe and record the initial condition of the shells in both containers (e.g., weight, appearance, color, integrity).
- Daily Observations:
- Have students observe and record changes in the appearance (discoloration, shell dissolution) and weight of the organisms or shells daily.
- Measure the pH of the water in each container each day.
- If the pH of the experimental container rises significantly, students should add small amounts of vinegar to maintain the target pH range. Record any additions of vinegar.
- Exit ticket
- If you opt to have students complete their notes using the Student Guided Notes format during your lecture, then use the bellringer as the exit ticket activity in class.
- If you opt to have students complete their notes using the Student Guided Notes format at home (homework), then use the following exit ticket activity:
- Exam Style Question #2 – page 206
Homework – high level/flipped classroom
- Version A – For High-Level Students:
Ideal for independent or advanced learners, this version requires students to copy all notes by hand as homework before class. This flipped-learning approach helps students come to class prepared, freeing up time for application activities, discussions, and AICE-style practice questions. - For this assignment have students fill in the blanks using the PPT Presentation. The Guided Notes can be found HERE.
Controlled experiments provide hands-on learning experiences, allowing students to directly interact with scientific concepts. This tactile engagement helps reinforce theoretical knowledge and makes abstract ideas more concrete and understandable.
More lessons…
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