diff --git a/sources/modules/compilation-model/translation-units.md b/sources/modules/compilation-model/translation-units.md
index 94141b3..e130183 100644
--- a/sources/modules/compilation-model/translation-units.md
+++ b/sources/modules/compilation-model/translation-units.md
@@ -3,4 +3,108 @@
 _Skeleton descriptions are typeset in italic text,_
 _so please don't remove these descriptions when editing the topic._
 
-This topic is currently under construction and will soon be filled with information :)
+### Overview
+
+_Provides a short natural language abstract of the module’s contents._
+_Specifies the different levels of teaching._
+
+------------------------------------------------------------------------
+Level             Objective
+----------------- ------------------------------------------------------
+Foundational      
+
+Main              ---
+
+Advanced          ---
+
+------------------------------------------------------------------------
+
+### Motivation
+
+_Why is this important?_
+_Why do we want to learn/teach this topic?_
+
+### Topic introduction
+
+_Very brief introduction to the topic._
+
+_TODO:
+_introduce notion of object file
+
+C++ Compilation model allows the developer to seperate their 
+declarations and definitions into various files so as to:
+
+* organize code logically,
+* facilitate reuse,
+* reduce rebuild times,
+* reduce file sizes and scopes,
+* avoid naming collisions,
+* and produce compiled libraries. 
+
+
+### Foundational: Building code from multiple files
+
+#### Background/Required Knowledge
+
+A student:
+
+1. Is able to define a variable, function, or class
+2. Is able to access declarations from either module import or header inclusion
+
+Questions:
+modules and/or functions?
+
+
+#### Student outcomes
+
+_A list of things "a student should be able to" after the curriculum._
+_The next word should be an action word and testable in an exam._
+_Max 5 items._
+
+A student should be able to:
+
+1. create a declaration for variables, functions, and classes separate from their definitions
+2. compile and link code from multiple implementation files
+3. explain how includes or imports work within their translation unit
+
+#### Caveats
+
+_This section mentions subtle points to understand, like anything resulting in
+implementation-defined, unspecified, or undefined behavior._
+
+#### Points to cover
+
+_This section lists important details for each point._
+
+Declarations and definitions can be within same file
+
+### Main: Organizing code across multiple translation units
+
+#### Background/Required Knowledge
+
+* All of the above.
+
+#### Student outcomes
+
+A student should be able to:
+
+1. package code into libraries
+2. explain trade-offs for placing code in header files vs implementation files
+
+#### Caveats
+
+#### Points to cover
+
+### Advanced
+
+_These are important topics that are not expected to be covered but provide
+guidance where one can continue to investigate this topic in more depth._
+
+A student should be able to:
+
+1. explain how an anonymous namespace functions within their translation unit
+2. One-definition-rule shennanigans
+3. Pimpl pattern
+4. Template definitions in translation unit it's used in?
+
+
diff --git a/sources/modules/external/graphical-user-interfaces.md b/sources/modules/external/graphical-user-interfaces.md
new file mode 100644
index 0000000..b63a124
--- /dev/null
+++ b/sources/modules/external/graphical-user-interfaces.md
@@ -0,0 +1,104 @@
+## External libraries: Desktop Graphical User Interfaces {#extern-gui}
+
+_Skeleton descriptions are typeset in italic text,_
+_so please don't remove these descriptions when editing the topic._
+
+### Overview
+
+_Provides a short natural language abstract of the module’s contents._
+_Specifies the different levels of teaching._
+
+------------------------------------------------------------------------
+Level             Objective
+----------------- ------------------------------------------------------
+Foundational:      Basic us of desktop graphical user interfaces
+
+Main:              Different forms of IO and accessibility
+
+Advanced:          Internationalization and customization
+
+------------------------------------------------------------------------
+
+### Motivation
+
+_Why is this important?_
+_Why do we want to learn/teach this topic?_
+
+For some applications a graphical user interface is beneficial. However, graphical user interfaces are not part of the C++ standard and external libraries are needed. We provide generic teaching goals and do not focus on a specific external library. Some mentionable libraries are: [Qt](https://www.qt.io/), [Cairo](https://www.cairographics.org/), and [wxWidgets](https://www.wxwidgets.org/). 
+
+### Topic introduction
+
+_Very brief introduction to the topic._
+
+### Foundational: Basic use of desktop graphical user interfaces
+
+#### Background/Required Knowledge
+
+A student: 
+
+1. should know linking libraries
+2. should know [header files](../compilation-model/headers.md)
+3. should know about [build systems](../compilation-model/buildsystems.md)
+
+#### Student outcomes
+
+_A list of things "a student should be able to" after the curriculum._
+_The next word should be an action word and testable in an exam._
+_Max 5 items._
+
+A student should be able to:
+
+1. link against the external library
+2. write an application with one window
+3. add simple widgets like text boxes and buttons to the window
+4. catch events of buttons or other elements
+5. explain the mechanics of event-driven programming
+
+#### Points to cover
+
+* use basic API functions
+* layout of the window
+* handle events by callbacks  
+
+#### Caveats
+
+_This section mentions subtle points to understand, like anything resulting in
+implementation-defined, unspecified, or undefined behavior._
+
+* programming user interfaces in C++ and in general require plenty of boiler plate code  
+* API calls are specific to one library and might not be transferable to other libraries
+* Some libraries are written in C 
+
+### Main: Different forms of IO and accessibility
+
+#### Background/Required Knowledge
+
+* All of the above.
+
+#### Student outcomes
+
+A student should be able to:
+
+1. add more advanced elements, like tables or images
+2. handle multiple windows
+3. show error and warning popups
+4. use different forms of IO, like keyboard, mouse, or touch pad
+5. explain basic of fonts and accessibility 
+
+#### Caveats
+
+*  programming user interfaces is rather complex and might not applicable for most students 
+
+#### Points to cover
+
+* More advanced API calls and design patterns
+
+### Advanced: Technicalities and tools
+
+_These are important topics that are not expected to be covered but provide
+guidance where one can continue to investigate this topic in more depth._
+
+* Internationalization
+* Font designers 
+* Hardware acceleration
+* Custom widget generation