Scientific Conclusions

Question

When making scientific conclusions, start with your CLAIM (what you think is happening), back it up with EVIDENCE, what you actually saw, measured, or observed in your experiment), and connect them with REASONING (explain WHY your evidence proves your claim using scientific facts you know).

⭐ Think of it like building a case: your claim is what you're trying to prove, your evidence is the clues you collected, and your reasoning is explaining how those clues prove your point using scientific knowledge!

CER Example and Walkthrough
Use this video to help you understand how to write using the CER process.
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Question 1
Using the CER framework, construct a scientific explanation addressing the following question:

Question 8: CLAIM

What is happening to the water quality of Lake Erie over time?

(1 point)
The water quality of Lake Erie is
decreasing
.
Question 2
Question 9: EVIDENCE.

Using the data table and graph below, provide evidence that will support your claim.





(2 points)
I know this is happening to the water quality in Lake Erie because the
pH
is
increasing
based on the data in Data Table 2.
Question 3
Question 10: REASONING
Explain how the abiotic (non-living) factor (pH, temperature, etc.) you chose in your evidence affects the health of the ecosystem in Lake Erie.

⭐Hints:

Review the graph and data chart and identify what information best supports your claim.
Think about how your chosen abiotic factor affects the health of the aquatic ecosystem
Review what can cause your chosen abiotic factor to get worse


Optional Sentence Starters:
“I know the (ph, surface temperature, size of the dead zone, or water clarity) of Lake Erie was getting (better or worse) because the numbers in the data table were…”
“When the (ph, surface temperature, size of the dead zone, or water clarity) gets worse, it can affect the aquatic ecosystem by…”
“The (ph, surface temperature, size of the dead zone, or water clarity) can negatively affect the aquatic ecosystem because…”

(4 points)

10000 Word Limit
Rubric

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Answer 1

Claim:
The water quality of Lake Erie is decreasing.

Evidence:
I know this is happening to the water quality in Lake Erie because the pH is increasing based on the data in Data Table 2. Specifically, the recorded pH levels have shown a notable upward trend over the past several years, indicating a decline in water quality, as the ideal pH range for aquatic life is between 6.5 and 8.5.

Reasoning:
The increase in pH levels in Lake Erie suggests that the water is becoming more alkaline. When the pH shifts out of the optimal range for aquatic organisms, it can cause stress to fish and other aquatic life. For instance, many species are sensitive to changes in pH, which can affect their respiration, reproduction, and overall health. Additionally, increased alkalinity can lead to harmful algal blooms, which further degrade water quality by depleting oxygen levels in the water and releasing toxins that can be harmful to both aquatic organisms and humans. This evidence indicates that the increasing pH level is negatively affecting the health and sustainability of the Lake Erie ecosystem.