diff --git a/journal/log_book_of_Yifan_XU_for_mooc-rr.md b/journal/log_book_of_Yifan_XU_for_mooc-rr.md
index e56ee9e4fd0c5980108499d1a92e87f64fad1407..36cc413fc8041b211333ae5c2e1fcfa94e16d8dc 100644
--- a/journal/log_book_of_Yifan_XU_for_mooc-rr.md
+++ b/journal/log_book_of_Yifan_XU_for_mooc-rr.md
@@ -44,11 +44,42 @@ Question: write a markdown file that has the same content as the given PDF file.
 This is what I am doing right now. Current time is June 11, 2025. I have finished the homework of module 1. The deadline for finishing the module 1 is June 13, 2025.
 
 
+## For module 2
+In module 2, Jupyter, a quite useful tool was introduced to us. In Jupyter, markdown is used for the text cells, and python can be used for the code cells. 
+Notably, the math symbols and formulations in text cells follow the syntax of Latex. 
+In addition, Jupyter is an online IDE, so we can directly write python code in the code cells of it without building any local environments and configurations. 
 
+## exercise 2-1: reproduce the PDF file about $\pi$
 
+State: finished.
 
+Note: use the jupyter to recover the content in that PDF file. when the python code is finished, run it to print or draw the figure.
 
 
+## exercise 2-2: compute mean value and min etc. of the given data
+
+State: finished.
+
+Note: use the functions in numpy to compute the mean value etc of the given data. One of the requirement is "Round to 2 decimal places".
+
+
+## exercise 2-3: draw a sequence plot and a histogram of the given data
+
+State: finished.
+
+Note: use matplotlib to draw a sequence plot and a histogram of the given data. When the python code is finished, run it to draw the figures.
+
+
+## exercise 2-4: record some interesting data and visualize it
+
+State: finished.
+
+Note: I searched and recorded the human population from 1900 to 2025 and that of France from 1900 to 2025. These data have been visualized in my Jupyter notebook. See it for details.
+
+## About the quiz
+
+To be honest, I found that some quizzes in this mooc are quite confusing, espicially the quiz 10. Some of its given "correct answer" have nothing to do with the related videos and documents. 
+