diff --git a/book/_toc.yml b/book/_toc.yml
index 6f7333b..2125e28 100644
--- a/book/_toc.yml
+++ b/book/_toc.yml
@@ -24,6 +24,7 @@ parts:
         - file: tutorials/cryocloud_demo/CryoCloud_demo.ipynb
         - file: tutorials/nb-to-package/index
           sections:
+            - file: tutorials/nb-to-package/OOP_intro
             - file: tutorials/nb-to-package/intro
               sections:
               - file: tutorials/nb-to-package/sample.ipynb
diff --git a/book/tutorials/nb-to-package/OOP_intro.md b/book/tutorials/nb-to-package/OOP_intro.md
new file mode 100644
index 0000000..23e02da
--- /dev/null
+++ b/book/tutorials/nb-to-package/OOP_intro.md
@@ -0,0 +1,13 @@
+# Intro to Object Oriented Programming (OOP)
+
+In this tutorial, we'll be learning how to structure object-oriented code 
+to take full advantage of this programming paradigm. 
+
+Follow along with the slides [`here`](./OOP.pdf)!
+
+We'll be using UCAR's ['Very Simple Climate Model'](https://scied.ucar.edu/interactive/simple-climate-model) as an example. 
+
+Go ahead and preview the code we'll write together
+- {download}`climate_model.py <./climate_model.py>`
+- {download}`co2_emissions.py <./co2_emissions.py>`
+- Some sample data: [`SSP_CO2emissions.csv`](./SSP_CO2emissions.csv)
diff --git a/book/tutorials/nb-to-package/climate_model.py b/book/tutorials/nb-to-package/climate_model.py
index f3e9b11..41c05bf 100644
--- a/book/tutorials/nb-to-package/climate_model.py
+++ b/book/tutorials/nb-to-package/climate_model.py
@@ -1,3 +1,6 @@
+# Very Simpl Climate Model
+##########################
+
 import numpy as np
 import matplotlib.pyplot as plt
 from co2_emissions import Constant_CO2, SSPEmissions