Grade: Grade 12 Subject: Science Unit: Science Electives Lesson: 6 of 6 SAT: ProblemSolving+DataAnalysis ACT: Science

Unit Checkpoint

Review

This checkpoint assesses your mastery of key concepts from the Science Electives unit. Before attempting the assessment, review the following topics:

Key Concepts from This Unit

From Advanced Topics and Interdisciplinary Science

  • Connections between scientific disciplines
  • Applying concepts across biology, chemistry, and physics
  • Current topics in scientific research
  • Real-world applications of scientific principles

From Investigation Lab

  • Components of the scientific method
  • Independent, dependent, and controlled variables
  • Control groups and experimental design
  • Replication and sample size
  • Formulating testable hypotheses

From Data and Graphs

  • Types of data (quantitative, qualitative, continuous, discrete)
  • Choosing appropriate graph types
  • Essential graph components (title, labels, scale, legend)
  • Statistical measures (mean, median, mode, range, standard deviation)
  • Correlation vs. causation

From CER Writing

  • Constructing clear, specific claims
  • Selecting relevant, quantitative evidence
  • Writing reasoning that connects to scientific principles
  • Avoiding common CER mistakes

Sample Problems with Solutions

Sample 1: Experimental Design

Question: A student wants to test how fertilizer concentration affects plant growth. Design an experiment identifying all variables.

Answer:

  • Independent variable: Fertilizer concentration (0%, 25%, 50%, 75%, 100%)
  • Dependent variable: Plant height (measured in cm weekly)
  • Controlled variables: Plant species, pot size, soil type, water amount, light exposure, temperature
  • Control group: 0% fertilizer (plain water)
  • Replication: 10 plants per concentration group

Sample 2: Data Analysis

Question: Given the data set 12, 15, 18, 15, 20, 15, 22, calculate the mean, median, and mode.

Answer:

  • Mean: (12+15+18+15+20+15+22)/7 = 117/7 = 16.7
  • Median: Ordered data: 12, 15, 15, 15, 18, 20, 22. Middle value = 15
  • Mode: 15 (appears 3 times)

Unit Assessment

Complete all problems to demonstrate your understanding of this unit.

1. A researcher studies the effect of music on plant growth. Plants in the music group grew an average of 12 cm, while silent group plants grew 11.5 cm. The researcher concludes music significantly helps plants. Evaluate this conclusion.

2. Identify the independent and dependent variables: A study examines how different amounts of sleep affect test performance in students.

3. What type of graph would best display changes in global temperature over the past 100 years? Explain your choice.

4. Calculate the range for this data: 45, 52, 38, 67, 41, 55, 49

5. Write a testable hypothesis for investigating whether caffeine affects heart rate.

6. A scatter plot shows a negative correlation between hours of TV watched and grade point average. Can you conclude that TV causes lower grades? Explain.

7. What three components must be included in a CER response? Describe the purpose of each.

8. Design an experiment to test whether salt concentration affects the boiling point of water. Include all variables and controls.

9. Given data showing enzyme reaction rates at different temperatures (10C: 5 reactions/min, 25C: 12 reactions/min, 37C: 25 reactions/min, 50C: 8 reactions/min, 70C: 0 reactions/min), write a complete CER explaining these results.

10. Why is random assignment of subjects to experimental groups important? What problem does it help prevent?

11. A student's graph has no title, unlabeled axes, and no units. List three specific improvements needed.

12. Explain the difference between precision and accuracy in scientific measurements. Give an example of each.

Check Your Understanding

Question 1: Which of the following best represents the reasoning component of a CER?

  • A) The temperature was 25 degrees Celsius
  • B) Higher temperatures increased the reaction rate
  • C) Kinetic molecular theory states that increased temperature causes faster molecular motion, leading to more frequent collisions
  • D) The experiment was conducted three times

Question 2: A valid scientific experiment must include:

  • A) Only qualitative observations
  • B) A control group and controlled variables
  • C) At least 100 subjects
  • D) Computer simulations

Question 3: Standard deviation measures:

  • A) The middle value of a data set
  • B) The most common value in a data set
  • C) The spread of data around the mean
  • D) The difference between the highest and lowest values

Question 4: When is a bar graph more appropriate than a line graph?

  • A) When showing change over continuous time
  • B) When comparing discrete categories
  • C) When displaying proportions of a whole
  • D) When showing frequency distribution

Next Steps

  • Review any topics where you struggled
  • Practice designing experiments for various research questions
  • Apply CER writing to lab reports and scientific explanations
  • Continue to other science units or SAT/ACT prep materials