There are a lot of methods to install python in chrome book. chrome book os works on Linux Kernal. so you can install python using Linux commands in chrome.
Step by Step guide to installing python in chrome BOOk
1. Open Terminal and run the following commands
sudo apt-get update
2. To check if your system already contains the run below command
3. If Python is not there then use the below command to install Python
$ sudo apt-get install python3.6
The above command is used to install the 3.6 version of python. To install another version change the version at the end of the command.