Mathematica quickie: About making cells Input cells by default

I'm going through some lecture notes, Fundamentals of Mathematica Programming (see 开发者_Go百科the .nb file there). I'd like to be able to do the exercises right there in the notebook; but for some reason I can't figure out how to make the default cell an Input cell. In other words, when I'm clicking in that notebook to create a new cell--in the exercises--the cell is by default a text cell. I'd like for it to be an Input cell so that I don't have to manually change it each time. Ideas?

The default cell style of a vanilla Mathematica install should already be "Input". It sounds like you perhaps are using an edited default stylesheet or have changed the preferences.

For recent versions (6.0+), go to Preferences, and under the Evaluation tab, make sure "Style of newly typed cells" is set to "Input", and that the drop-down below it labeled "Format type of new input cells" is set to "StandardForm".

For older versions, make sure Cell → Default Input FormatType in the menu is set to StandardForm. To check/change the default cell input type, open Format → Option Inspector... in the menu and navigate to Cell Options → New Cell Defaults and set DefaultNewCellStyle to "Input".

You can set the scope of the Option Inspector to global or notebook in the dropdown at the top. The particular notebook you linked to has the default style set to "Text" which is the problem.