Added Excercise section to some lessons

curriculum/04-python-foundations/01-output-variable-datatypes.md

@@ -157,6 +157,11 @@ We will learn how to read and deal with errors in later lessons.
 
 :::
 
+## Excercise
+Visit our [python-excercise repository](https://github.com/ThePythonLedger/python-exercises) and follow instructions there to *fork* and *clone* your own copy of excercises repository.
+
+After cloning, try to solve [excercise-1](https://github.com/ThePythonLedger/python-exercises/tree/main/exercises%2Ffoundations%2F01_hello_world) and [excercise-2](https://github.com/ThePythonLedger/python-exercises/tree/main/exercises%2Ffoundations%2F02_datatypes) for better understanding.
+
 ## Assignment {#assignment}
 Try the following excercise to establish your knowlege. We will build a shop, starting with defining (declaring) diffrent variables in this lesson and progress with our little shop as we go further along.
 

curriculum/04-python-foundations/02-math-stringops-comparisons.md

@@ -211,6 +211,9 @@ print((6 < 7) or (8 > 4)) # True
 print(not True) # False
 ```
 
+## Excercise
+Try to solve [excercise-3](https://github.com/ThePythonLedger/python-exercises/tree/main/exercises%2Ffoundations%2F03_math_and_comparisons) for better understanding.
+
 ## Assignment
 In the last assignment we have declared our shop variables and printed the inventory. In this one you are tasked with:
 1. Open your code editor in your last project directory `simple-python-shop`