diff --git a/book/syntax_exercises/009.md b/book/syntax_exercises/009.md
index af3c4b0..ce51f6f 100644
--- a/book/syntax_exercises/009.md
+++ b/book/syntax_exercises/009.md
@@ -19,7 +19,29 @@ Using properly formatted equations makes mathematical expressions clearer and mo
 $$ F_{res} = m \cdot a $$ 
 ```
 
-3. Now, add an inline equation by enclosing the equation with single dollar signs. Try this example:
+```{tip}
+The syntax used for creation equations is TeX, a markup language for math. It's often part of the software-system LaTeX, which allows to create full documents in this language. There's plenty of documentation online on how to use it, including graphical interfaces (for example [this one](https://latexeditor.lagrida.com/))
+```
+
+3. Now let's add another equation with an error:
+
+```md
+$$ E = m \ccdot c^2 $$
+```
+
+4. Check whether the equations renders correctly by clicking `preview`. Note that all ill-formatted equation are indicated in red, i.e. $\red{\text{\ccdot}}$
+
+5. As an alternative you try and use the 'math directive'. This will have the same results + adds a equation number which can be used for referencing:
+
+````md
+```{math}
+v = a \cdot t
+```
+````
+
+6. Click on `preview` again. Note that these equations don't render. That's because the 'math directive' is a MyST feature (an extension of markdown), which is not supported by the GitHub previewer that only support markdown.
+
+7. Now, add an inline equation by enclosing the equation with single dollar signs. Try this example:
 
 
 ```md
@@ -28,7 +50,7 @@ The displacement can be found using the equation $s = v \cdot t$.
 
 ## Formatting mathematical symbols
 
-4. In this step we will experiment with different LaTeX symbols. Use the following table and test each example in your Markdown file:
+8. In this step we will experiment with different TeX symbols. Use the following table and test each example in your Markdown file:
 
 
 | Name | Script |
@@ -40,7 +62,7 @@ The displacement can be found using the equation $s = v \cdot t$.
 | Superscript | `^{N}` | 
 | Multiplication | `\cdot` | 
 
-5. Extend this exercise by trying more advanced mathematical expressions:
+9. Extend this exercise by trying more advanced mathematical expressions:
 
 | Name | Script | 
 |---|---|
@@ -48,15 +70,15 @@ The displacement can be found using the equation $s = v \cdot t$.
 | Integral | `\int_a^b dx` | 
 | Sine function | `\sin(x)` | 
 
-6. Test your understanding by adding a new equation of your choice, ideally one that requires many LaTex symbols!
+10. Test your understanding by adding a new equation of your choice, ideally one that requires many LaTex symbols!
 
-7. When you are ready, commit your changes to the repository by clicking on the green `Commit changes` button.
+11. When you are ready, commit your changes to the repository by clicking on the green `Commit changes` button.
 
-8. Add a commit message.
+12. Add a commit message.
 
-9. To see your changes, go to {octicon}`play;1em` `Actions` - The most recent workflow run `overview.md / the commit message of the commit you just made` - Wait for it to finish - In the summary, click on the link of your book shown in the table `Branches deployed` and under `Primary book at root` (getting bored of waiting? There'll be exercising on doing this locally which prevents you from waiting).
+13. To see your changes, go to {octicon}`play` `Actions` - The most recent workflow run `overview.md / the commit message of the commit you just made` - Wait for it to finish - In the summary, click on the link of your book shown in the table `Branches deployed` and under `Primary book at root` (getting bored of waiting? There'll be exercising on doing this locally which prevents you from waiting).
 
-10. Do you see your change? If you don't see it click `CTRL`+`F5`/`Control`+`F5`to refresh the page.
+14. Do you see your change? If you don't see it click `CTRL`+`F5`/`Control`+`F5`to refresh the page.
 
 
 ```{admonition} Check your understanding
@@ -64,7 +86,8 @@ The displacement can be found using the equation $s = v \cdot t$.
 
 Before moving on to the next exercise, make sure you understand the following:
 - What is the difference between inline and block equations?
-- How do you use LaTeX formatting for different mathematical symbols?
-
+- How do you use TeX formatting for different mathematical symbols?
+- What is the purpose of using single vs. double dollar signs for equations?  
+- How do you troubleshoot if your equations are not rendering correctly?  
 ```