Notebook file does not open, can someone

We got the horizontal throw in physics lessons and got a file sent to us. The file has the teacher but written by smartboard and the file is a notebook file can someone tell me how to open this or can someone convert the open one?

Which extension does the file have?

Abdc.xlm, Abcsde.doc, etc?

.notebook

With the program: smart notebook

https://www.smarttech.com/de-de/products/education-software/smart-learning-suite