Visualization Practices

CUED 7540: Learning Analytics III

Author

Faith Lee, faith.n.adkins@gmail.com

Published

October 6, 2025

Learning Objectives

By the end of this lesson, you will be able to:

- Generate basic analytics plots using ggplot2.

- Customize plots for better data visualization.

- Interpret different types of visualizations to gain insights.

- Understand how to apply visualization to different data analysis tasks.

Part 1: Loading and Exploring Data**

Before we start creating plots, we need to load and inspect the datasets we’ll be working with. We’ll use a new dataset called educational_data.csv.

Task 1: Load the educational_data.csv dataset and inspect its structure. This will help you understand what variables you’re working with.

Reflect & Respond

Question 1: What Catches Your Eye? As you browse through the dataset, what stands out to you? Is there anything that piques your curiosity? Maybe a surprising trend or a pattern you didn’t expect?

  • [The students who had a 100 in homework completion had lower quiz and final exam scores than I expected. Also, the student with the lowest study hours had fairly high grades for everything else, even the homework completion. That student also scored better than the student with the most study hours (besides the final grade).]

Question 2: What Questions Do You Have? Is there something specific you’d like to dig deeper into? Think about what you might want to learn more about. Are there any relationships between variables you’re curious about?

  • [Why were quiz/exam scores lower than expected for the students with the highest homework completion? Does this mean the homework needs to be adjusted? I am also interested in seeing if there are any significant differences between the male and female students’ scores.]

Question 3: What’s Your Analytics Game Plan? How would you approach analyzing this dataset? What steps would you take to uncover the insights you’re interested in?

  • [I would look for averages for each of the scores, homework completion, and study hours. I think it would also be beneficial to create graphs to visualize the relationships. I would also get more specific and break the graphs down into smaller subgroups (ex. male vs female).]

Part 2: Visualizing Relationship and Scatter Plots

Scatter plots are useful for visualizing the relationship between two continuous variables. The gg in ggplot stands for “Grammar of Graphics,” which means we build plots in layers.

Scatter Plot

Task 2: Create a scatter plot to explore the relationship between Study_hours and Quiz_Score. This plot will help you visualize if there’s a correlation.

# Create a scatter plot of Study_hours vs. Quiz_Score with a regression line

ggplot(data3, aes(x = Study_Hours, y = Quiz_Score)) +
  geom_point(color = "blue", size = 3, alpha = 0.6) +
  geom_smooth(method = "lm", color = "red", se = TRUE) +  # This line will add a linear regression line
  labs(title = "Scatter Plot of Study Hours vs. Quiz Score", 
       x = "Study Hours (Hours)",
       y = "Quiz Score") +
  theme_minimal() +
  theme(
    plot.title = element_text(size = 16, face = "bold", hjust = 0.5),
    axis.title.x = element_text(size = 12, face = "bold"),
    axis.title.y = element_text(size = 12, face = "bold")
  )
`geom_smooth()` using formula = 'y ~ x'

Task 3: Now that we’ve visualized the relationship, let’s compute the correlation between the two variables to get a numerical value for their relationship. The use = "complete.obs" argument handles any missing values by only using the rows that have data for both variables.

# Compute the correlation
# COMPLETE YOUR CODE BELOW
correlation <- cor(data3$Study_Hours, data3$Quiz_Score, use = "complete.obs")

# Display the correlation
correlation
[1] -0.04308071

Reflect & Respond

Question: What does the correlation value tell you about the relationship between study hours and quiz scores?

  • [The correlation value doesn’t seem to show much of a relationship between study hours and quiz scores, so studying does not have a meaningful relationship with quiz score.]

Activity: Customize the Scatterplot

# Create a scatterplot of 'Quiz_Score' vs 'Final_Exam_Score'
ggplot(data3, aes(x = Quiz_Score , y = Final_Exam_Score)) + #COMPLETE THE CODE
  geom_point(color = "red", size = 3, shape = 16) +
  labs(title = "Scatter Plot of Quiz Score vs. Final Exam Score", x = "Quiz Score", y = "Final Exam Score") +
  geom_smooth(method = "lm", color = "blue", se = TRUE) +
  theme(
    plot.title = element_text(size = 16, face = "bold", hjust = 0.5),
    axis.title.x = element_text(size = 12, face = "bold"),
    axis.title.y = element_text(size = 12, face = "bold")) +
  facet_wrap(~Gender)
`geom_smooth()` using formula = 'y ~ x'

Let’s customize the relationship between Quiz_Score and ‘Final_Exam_Score’.

  1. Change the size of the points to make them more prominent. You can also experiment with different shapes (e.g., circles, triangles, squares) Hint: add ‘size = 3, shape = 16’ inside geom_point(). Numbers can change.

  2. Add a linear regression line to your scatter plot to see the trend between variable 1 and variable 2. *Hint: Use geom_smooth()

  3. Update the title and the axis labels. Make the title bold and center it.

  4. Use facet_wrap() to create separate scatter plots based on Gender. *Hint:facet_wrap()

  5. Exercise with the {scatterplot-activity} chunk below.

# Create a scatterplot of 'Quiz_Score' vs 'Final_Exam_Score'
# COMPLETE THE CODE ------> I did all of this on the code chunk above assuming I had to change it instead (hopefully that is correct).
ggplot(data3, aes(x = Quiz_Score, y = Final_Exam_Score)) +
  geom_point(color = "blue",size = 3, shape = 10) +
  labs(title = "Scatterplot of Quiz Score vs Final Examp Score", x = "Quiz Score", y = "Final Exam Score")+
geom_smooth(method = "lm", color = "lightpink", se = FALSE)+
  theme(plot.title = element_text(size = 16, face = "bold", hjust = 0.5)) 
`geom_smooth()` using formula = 'y ~ x'

Part 3: Histogram

Histograms are used to visualize the distribution of a single continuous variable. Let’s create a histogram of Homework_completion.

# TYPE YOUR CODE FOR THE X VARIABLE BELOW
ggplot(data3, aes(x = Homework_Completion)) +
  geom_histogram(binwidth = 4, fill = "cyan", color = "blue") +
  theme_classic() +
  geom_vline(xintercept = mean(data3$Homework_Completion, na.rm = TRUE)) +
  facet_wrap(~Gender) +
  labs(title = "Histogram of Homework Completion Frequency", x = "Homework Completion", y = "Frequency") #update your titles

Activity: Customize the Histogram

  1. Change the fill and color of the bars to something else. You can choose any colors you like! Use the link provided earlier for color options. color names

  2. Change the binwidth, and observe how the histogram changes. What happens if you set it to different numbers?

  3. Update the title and the x-axis to something that is relevant to your analytics.

  4. Apply the theme_minimal() and see how it changes the look of your plot. Try out other themes like theme_classic() or theme_dark(). *Hint - You can add +theme_minimal() at the end of the code line.

  5. Add a vertical line at the mean of the variable to highlight the average value. Use geom_vline(). The mean() function with na.rm = TRUE will ignore missing values.

  6. Use facet_wrap() to create separate scatterplots ffor a categorical variable like Gender. For example, if you want two scatterplots based on ‘Gender’ variable, the syntax is +facet_wrap(~Gender).

  7. Use the histogram-activity chunk below to practice.

# Customize the histogram of the 'Homework_completion' variable
# COMPLETE THE CODE
ggplot(data3, aes(x = Homework_Completion)) +
  geom_histogram(binwidth = 2, fill = "blue", color = "purple") +
  labs(title = "Histogram of Homework Completion Frequency", x = "Homework Completion", y = "Frequency")+
theme(plot.title = element_text(size = 16, face = "bold", hjust = 0.5))+
  theme_dark()+
  geom_vline(aes(xintercept = mean(data3$Homework_Completion, na.rm = TRUE)),
           color = "red", linetype = "dashed", size = 1)
Warning: Using `size` aesthetic for lines was deprecated in ggplot2 3.4.0.
ℹ Please use `linewidth` instead.
Warning: Use of `data3$Homework_Completion` is discouraged.
ℹ Use `Homework_Completion` instead.

Part 4: Exploring Grouped Data with Box Plots

Boxplots are useful for visualizing the distribution of a variable across different categories and identifying potential outliers.

Box Plot

Let’s create a box plot of Homework_Completionby Gender.

# Create a boxplot of 'Homework_Completion' by 'Gender'
# COMPLETE THE CODE
ggplot(data3, aes(x = Gender, y = Homework_Completion , fill = Gender)) +
  geom_boxplot(color = 'black', fill = 'blue') +
  labs(title = "Boxplot of Homework_Completion by Gender", x = "Gender", y = "Homework Completion") +
  theme(plot.title = element_text(size = 16, face = "bold", hjust = 0.5)) +
  geom_boxplot(outlier.colour = "red", outlier.shape = 16, outlier.size = 3)

Activity: Customize the Boxplot

  1. Change the fill colors for the boxes.

  2. Add color = “black” (or some other color) to the geom_boxplot() to set the color of the box outlines.

  3. Update the title and the y-axis label properly. Make the title bold and center it. **Hint: ** Add +theme(plot.title = element_text(size = 16, face = "bold", hjust = 0.5))

  4. Customize the outliers by changing their shape and color. For example, make outliers larger and red by adding +geom_boxplot(outlier.colour = "red", outlier.shape = 16, outlier.size = 3)

  5. Use the boxplot-activity chunk below to practice.

# Create a boxplot of 'Homework_Completion' by 'Gender'
# COMPLETE THE CODE
ggplot(data3, aes(x = Gender, y = Homework_Completion, fill = Gender)) +
  geom_boxplot(color = 'black') +
  labs(title = "Homework Completion by Gender", x = "Gender", y = "Homework Completion")+
  theme(plot.title = element_text(size = 16, face = "bold", hjust = 0.5))+
  theme(legend.position = "none")

Part 5: Counting Categories with Bar Plots

Bar plots can display the counts of different categories in your data.

Task 5: Visualize the count of students by Gender.

# Create a bar plot of counts of 'Gender'
# COMPLETE THE CODE BELOW
ggplot(data3, aes(x = Gender)) +
  geom_bar(fill = "yellow", color = "black", width = 0.75) +
  labs(title = "Count of Students by Gender", x = "Gender", y = "Count") +
  theme(plot.title = element_text(size = 16, face = "bold", hjust = 0.5))

Activity: Customize the Bar Plot

  1. Change the fill color of the bars.

  2. Change the width of the bars by using the width parameter inside geom_bar(). (i.e., width = 0.5)

  3. Update the title and the y-axis labels to be descriptive. Make the title bold and center it.

  4. Use the barplot-activity chunk below to practice.

# Create a bar plot of counts of 'Gender'
# COMPLETE THE CODE
ggplot(data3, aes(x = Gender)) +
  geom_bar(width = , fill = "purple", color = "black") +
  labs(title = "Student Counts by Gender", x = "Gender", y = "Count")+
  theme(axis.text.x = element_text(angle = 90, hjust = 1))+
scale_fill_manual(values = c("F" = "pink", "M" = "blue"))+
  theme(plot.title = element_text(size = 16, face = "bold", hjust = 0.5))
Warning: No shared levels found between `names(values)` of the manual scale and the
data's fill values.

Final Reflection : How can we use LA in instructional design and decision?

After practicing the basic analysis and visualization techniques for the past couple of weeks, take some time to reflect on how these skills can be applied in the real world.

  1. Consider the role of an educator, instructional designer, curriculum developer, policymaker, etc. How might the ability to analyze and visualize data help you make informed decisions, improve learning outcomes, or design more effective educational experiences? Think broadly about the implications of these skills in your current or future professional context, and share your thoughts on how data-driven insights could enhance your work.
  • [In the role of an educator, analyzing data about the classroom is how we can discover ways of improvement or identify students that need intervention. Similar to what we did in this practice, teachers can analyze quiz/test grades, homework scores, and studying time. Using these statistics, teachers can reevaluate their content and instruction. Attendance and participation can be monitored as well and be used as a comparison for grades, or simply as a visual for communication with students and their parents. For further visualization during parent-teacher conferences, teachers can also track students’ homework completion. Creating graphs and charts to help visualize student data is not only beneficial for organizing the data in one place, but it can also provide insights into areas of improvement.]

Render & Submit

Congratulations, you’ve completed the module!

To receive full score, you will need to render this document and publish via a method such as: Quarto Pub, Posit Cloud, RPubs , GitHub Pages, or other methods. Once you have shared a link to you published document with me and I have reviewed your work, you will be officially done with the current module.

Complete the following steps to submit your work for review by:

  1. First, change the name of the author: in the YAML header at the very top of this document to your name. The YAML header controls the style and feel for knitted document but doesn’t actually display in the final output.

  2. Next, click the “Render” button in the toolbar above to “render” your R Markdown document to a HTML file that will be saved in your R Project folder. You should see a formatted webpage appear in your Viewer tab in the lower right pan or in a new browser window. Let me know if you run into any issues with rendering.

  3. Finally, publish. To do publish, follow the step from the link

If you have any questions about this module, or run into any technical issues, don’t hesitate to contact me.

Once I have checked your link, you will be notified!