Hi, these are my suggestions that I hope you will develop it in this app:

1- add Cartesian coordinate system because draw it every time is uncomfortable.
2- I hope that moving from one page to another will be from up to down not from left to right because that gives you sensibility of the connections between the pages or let this as an option in the app.
3- Support right-to-left languages such as Arabic, please. We are suffering from this.
4- When we choose to write why don't you put a color box on the top of the page with the most famous colors such as blue and red so we can change the color easily.
5- Put an option to add a table and a chart.
6- put a basic figures of some famous functions such as X^2 and 1/x.

Please look at these suggestions.

Thanks.