Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Define matter and identify its different states.
• Describe the physical and chemical properties of matter.
• Apply the scientific method to investigate a problem.
• Discuss the implications of matter in real-life.

Lesson summary

Welcome, future scientists and problem-solvers! In our study of Chemistry, we don't just learn facts about matter; we learn *how* we discovered those facts. The scientific method is the powerful, systematic process that scientists use to ask questions and find reliable answers about the world around us. In Ghana, from understanding why our kenkey spoils faster on a hot day to finding solutions for plastic waste in our communities, the scientific method gives us a tool to turn curiosity into knowledge and action. This lesson will equip you with the skills to think like a scientist and solve real-world problems.

Lesson notes

The scientific method is not a rigid checklist but a flexible and logical process for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. It is the backbone of all scientific disciplines, including Chemistry.

Let's break down the typical steps using a common Ghanaian scenario: Why does boiled water with a little bit of salt added seem to cook food like yam or rice faster? Step 1: Observation This is the starting point. It involves noticing something in the natural world using your senses (sight, hearing, smell, touch, taste) or measurement tools. Observation: My grandmother always adds a pinch of salt to the water when boiling yam. I have noticed that the yam seems to get soft more quickly than when I forget to add salt. Step 2: Question / Problem Based on your observation, you ask a question that you want to answer. A good scientific question is specific and testable. Vague Question: Why is salt special? Good Scientific Question: Does adding salt to water affect the time it takes to boil yam until it is soft? Step 3: Hypothesis A hypothesis is a proposed, testable explanation for an observation. It is an educated guess, not just a random guess. It is often written as an "If..., then..." statement. A good hypothesis must be *falsifiable*—meaning it can be proven wrong. Hypothesis: If salt is added to water, then it will raise the boiling point of the water, causing the yam to cook at a higher temperature and therefore cook faster. Step 4: Experimentation This is the process of testing your hypothesis. A well-designed experiment is crucial for getting reliable results. The key is to control variables.

What are Variables? Variables are any factors that can change or be changed in an experiment. There are three main types: Independent Variable: The one factor that *you* intentionally change or manipulate. *In our example:* The presence or absence of salt in the water. Dependent Variable: The factor that you *measure* or observe to see how it is affected by the change in the independent variable. *In our example:* The time it takes for the yam to become soft. Controlled Variables (or Constants): All other factors that must be kept the same for all test groups to ensure a fair test. If these are not controlled, you won't know if your independent variable was the true cause of the result. *In our example:* The amount of water used. The size and type of the yam pieces. The type of cooking pot. The heat source (e.g., the same setting on the gas cooker). The amount of salt used (if testing different amounts).

Experimental Setup: Control Group: A group that is treated exactly the same as the experimental group, but without the independent variable. It serves as a baseline for comparison. *Our Control Group:* A pot with yam boiling in plain water. Experimental Group: The group where the independent variable is applied. *Our Experimental Group:* A pot with yam boiling in salt water. Step 5: Data Collection and Analysis This involves systematically recording your observations and measurements from the experiment. Data is often organized into tables and then visualized using graphs. Data Collection: You would use a stopwatch to record the cooking time for both pots. You might repeat the experiment 3 times (3 trials) to ensure your results are consistent and not just a fluke. Sample Data Table: | Trial | Time to Cook in Plain Water (minutes) | Time to Cook in Salt Water (minutes) | | :---- | :------------------------------------ | :----------------------------------- | | 1 | 25 | 21 | | 2 | 24 | 22 | | 3 | 26 | 21 | | Average | 25.0 | 21.3 | Analysis: Calculate the average time for each group. The data clearly shows that, on average, the yam in salt water cooked faster. Step 6: Conclusion After analysing the data, you state whether your hypothesis was supported or rejected. Conclusion: The results show that yam cooked in salt water became soft in an average of 21.3 minutes, while yam in plain water took an average of 25.0 minutes. Therefore, the data supports the hypothesis that adding salt to water decreases the cooking time for yam. (A further scientific explanation would confirm this is due to boiling-point elevation). Step 7: Communication (Reporting Results) Scientific knowledge grows when findings are shared. Scientists communicate their results through reports, posters, journal articles, and presentations. This allows other scientists to review, replicate, and build upon the work (this is called peer review). *In our class:* We will design a poster to share our findings, as suggested by the NaCCA exemplar.

Evaluation guide

• Investigate the scientific method of inquiry.
• I
• nquiry-B ased Learning:
• In mixed-gender groups,