Start by having students students try this challenge. After that, students will learn how to draw triangular numbers, and how to find the \(n\)th triangular number by adding. For example, to find the \(4\)-th triangular number, we do \(1 + 2 + 3 + 4.\) Conclude by giving your students the challenges found here and here.
Conclude by leading this investigation:
Half Fraction Snake