Open Middle - A Collection of Challenging Problems

Just found this great site today and plan on incorporating it into my problem library. It has a fresh approach:

http://www.openmiddle.com/

Here is their explanation of the site, listed under the "about" link:

Dan Meyer introduced us to the idea of “open middle” problems during his presentation on “Video Games & Making Math More Like Things Students Like” by explaining what makes them unique:

• they have a “closed beginning” meaning that they all start with the same initial problem.
• they have a “closed end” meaning that they all end with the same answer.
• they have an “open middle” meaning that there are multiple ways to approach and ultimately solve the problem.

Open middle problems require a higher depth of knowledge than most problems that assess procedural and conceptual understanding.   They support the Common Core State Standards and  provide students with opportunities for discussing their thinking.

Some additional characteristics of open middle problems include:

• They often have multiple ways of solving them as opposed to a problem where you are told to solve it using a specific method. Example
• They may involve optimization such that it is easy to get an answer but more challenging to get the best or optimal answer. Example
• They may appear to be simple and procedural in nature but turn out to be more challenging and complex when you start to solve it. Example
• They are generally not as complex as a performance task which may require significant background context to complete. Example