Some people believe that math classes in school should focus only on direct instruction of math, and projects and other group assignments mean less time to study math, so less math would be learned. The teenagers might dislike the monotonous math classes focused only on direct instruction, but, the thought process goes, years later they'll thank you because they actual know enough math to pursue a career while their peers in the less focused math classes aren't being hired.
But I don't follow that philosophy on this blog -- simply because a believer in the direct instruction method doesn't even need to read a blog to find adequate teaching material. If a teacher is searching for the blogs of fellow math instructors online, then that teacher most likely is looking for special projects to implement in the classroom -- not just lecture notes. The most successful math teacher blogs focus on special projects, and so I wish to include such on my blog as well.
I like to gather such activities from various sources, to see which ones I like -- for if I draw only from a single source, the reader would simply go to my source and not read this blog. My main source is, of course, the U of Chicago text. But I also draw from other geometry texts as well as other math teacher blogs.
Now I remember once reading a geometry text and, interspersed throughout the second chapter on logic, there were a number of interesting logic puzzles. Since I'm right now in the logic chapter, why shouldn't I include some logic puzzles as well?
In searching for logic puzzles, I found the website of John Pratt, an astronomy professor from Utah:
What I like about this list of 20 problems is that two of them are identical to the problems I saw in that other geometry text -- Puzzles 4 and 8. And so I decided to take the first ten problems and make them into an activity worksheet.
Now how can teachers use this worksheet? I don't expect any student to discover the answers to all ten problems during a single class period. But perhaps a teacher can divide the class into ten groups and give a different puzzle to each group. Indeed, it's possible to use differentiation here -- since Dr. Pratt writes that he arranged the puzzles from easiest to hardest, a teacher can assign the first few problems to the lower performing groups. Pratt states that elementary students (and hopefully, the lower performing high school students) can solve the first few problems.
I don't include the answers here. Teachers can either solve the puzzles themselves or get the answers directly from Pratt's website.