Primitive Lightning (composite divisors)

Primitive Lightning (composite divisors)

Show your class a lightning strike with the number 88. This is how it looks. Pause for two minutes. Let them try to figure out some of the rules governing its construction. You can think too. What observations do you make? Here is a possible list: When a split occurs...
Jumping Frogs (patterns, counting, primes)

Jumping Frogs (patterns, counting, primes)

Jumping Frogs (MathPickle, 2017) The last puzzle in the video above was solved in 2025 by Joseph Burke, a student in Megan McKee’s grade 4 class. Spoiler alert! Here it is…  Jumping Frogs is a fantastic base to create both casual and complex puzzles. We...
Celtic Counting (counting, proof)

Celtic Counting (counting, proof)

Celtic Counting requires students to trace an under and over pattern – counting the Celtic loops. How many loops exist in this knot? There are two. How many loops does this knot have? There are three. The following slides have larger knots, but students age 6+...
EKG Sequences – factorization

EKG Sequences – factorization

Tree of Numbers – EKG Sequences (MathPickle, 2014) Student groups should work independently and then collaboratively to find when these integer sequences converge. Neil Sloane introduced me to the first EKG sequence in 2014. Its beauty and suitability for the...
1-100 Composite Connector Challenge

1-100 Composite Connector Challenge

1-100 Composite Connector Challenge This is a challenge for a class that has nothing to do except rejoice in connecting numbers that share common prime factors. The highest score that I've managed is 195, but I don't use computers so this can almost certainly be...