# Author Archives: Dave Youngs

### 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

### Have You Done a Good Math Problem Lately?

In work or social settings it is common to hear the question, “Have you read a good book lately?” The question often starts a lively sharing session about books that elicit pleasure, profundity, or insight. A population that regularly engages in these discussions is an indicator of a literate society. As those appointed by society… 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

### 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

### The Envelope Enigma

This weeks’s activity comes from the field of recreational mathematics. While the puzzle may not seem very mathematical (other than using mathematical language like points and line segments), it is actually related to the mathematical fields of network theory and topology. In this puzzle, students are asked to connect six points (labeled A-E) with line… Continue Reading