Do you really need a book for this? It seems pretty easy to dream up any number of very simple problems:
Convert temperature, currency, etc. from one unit to another.
Input several parameters and output the result of a calculation based on those parameters:
- Inputs: mass, acceleration; Output: force
- Inputs: any two of voltage, current, resistance; Output: the missing value
- Input: a chemical formula; Output: properties of that compound such as molecular weight
Basic mathematical computations:
- Find the first 6 or 7 perfect numbers
- Find the first n prime numbers
- Factor a number
Basic data storage:
- Create a to-do list, address book, calendar, etc.
- Use a data file, such as a table of elements, to calculate something
I could go on like this all day.
If you're going to be teaching a class, you might want to think bigger. Think of some larger project, and then break it down into simpler, smaller problems. Then you can assign the simpler problems first and work toward putting those skills together into something interesting. For example, you might decide to have students build a web server. That might sound really complicated, but web servers can actually be very simple: accept a request, figure out what to send back, and send the data. So, start by having students accept inputs from stdin, calculate something, and print an output to stdout. Then teach them to use files. Then show them that reading/writing from/to a network connection is just like reading and writing a file. A simple web server can be up and running pretty quickly, and after that you can start adding features like logging, permissions, etc.