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# Puzzle

### The Three-to-Five Triangle Puzzle

This week’s Puzzle Corner activity comes out of a rich historical tradition that dates back to the 19th century when matches were first manufactured. Invented in 1827 by the British chemist John Walker, matches soon replaced the tinderboxes that people had formerly used to light fires. As matches grew in popularity and became ubiquitous later… Continue Reading

### Locating Legs

This week’s Puzzle Corner activity has a holiday theme. In it, students are presented with a paradoxical scenario and asked to try to make sense of it. In this scenario a child is hiding under a table at her parent’s holiday party. Looking out, she can count 20 legs and thus knows there are 10 adults in… Continue Reading

### Total Count-Ability

How many different answers can you find and justify for the nursery rhyme Going to St. Ives? As I was going to St. Ives I met a man with seven wives. Every wife had seven sacks, Every sack had seven cats, Every cat had seven kits. Kits, cats, sacks and wives, How many were going… Continue Reading

### Cab Conundrum

This week’s puzzle is a modification of a brain teaser that has been around for many years—the hotel problem. In the original version of the mathematical paradox, three men pay ten dollars each for a thirty dollar hotel room. Later, they receive a five dollar refund. Because they cannot easily split the five dollars, they each… Continue Reading

### Penny Penning Puzzle

This week’s puzzle is a good one to use early in the school year. It is fairly easy and shouldn’t frustrate students too much in their early exposure to the puzzle-solving process. To do this puzzle, students need only the student sheet depicting the nine-penny arrays and a pencil. The puzzle challenges students to draw… Continue Reading

### Family Ties

This weeks’s Puzzle Corner activity is a collection of three riddles all dealing with the relationships between relatives. The first one is thought to be many hundreds of years old and is one of the best known brainteasers of all time. I have chosen to leave it in its original form, even though the style of English… Continue Reading

### Matching Marbles

This activity fits in a category normally called logic problems. Logic problems usually don’t require calculations of any sort, making them different from most other math problems. To solve these types of problems, logical or mathematical thinking must be used. Matching Marbles is a perfect example of this type of problem because to solve it, students must… Continue Reading

### The Problem of Anwar’s Camels

I just started reading Fractions in Realistic Mathematics Education by Leen Streefland, and there, on page 5, Streefland gives as an example an old puzzle problem that I remember giving my students more than 40 years ago. “An old Arab, Anwar his name, decreed before he died that his eldest son inherit one-half, his second… Continue Reading

### Ocean Anagrams

This week’s Puzzle Corner activity has an ocean theme. In it, students are presented with a number of anagrams. Anagrams are words or collections of words whose letters are rearranged to form new words or collections of words. For example, an anagram for canoe is ocean. Anagrams have a long history in the puzzle community. Lewis Carroll, who was really… Continue Reading

### How to Make Your Own O’Beirne’s Puzzle

Last week I showed you the O’Beirne puzzle and 30 of you very quickly responded to the offer of a free puzzle. I hope you’ve gotten it by now. In future posts I’ll explore with you some ways to use the puzzle to engage students with Common Core Standards for Mathematical Practice as well as… Continue Reading