The following student text on conservation laws, symmetries, and elementary particles was developed in a Dutch project for teaching modern physics to the top stream of the sixth year of secondary education (age 17–18). In a series of 35 lessons of 45–50 minutes each, students study particle-wave duality, the Heisenberg principle, probability models for properties of particles, the particle in a box, and applications, elementary particles, and astrophysics (http://www.phys.uu.nl/∼wwwpmn). In this paper we focus on particle physics and the key concepts of this chapter are: transformation, reaction equation, conservation laws, and symmetry. For recent literature regarding the teaching of symmetries and/or elementary particles, we refer to articles by Hill & Lederman,1 Pascolini & Pietroni,2 Kalmus,3 O'Connell,4 and Hanley.5