From http://songersmusic100.blogspot.com/2014/01/05-dynamics-timbre-and-organizing.html

Dynamics are the when you make sounds louder or softer.

When you write a dynamic marking under a note, such as p (for piano, or “soft”), the person singing or playing the song will know to play it softly. When you use dynamic markings (pp, p, mp, mf, f, ff) in a piece of music, it can make the song so much more interesting and beautiful. You can make it sound more like you want it to!

You can also mark a crescendo or decrescendo under your notes if you want to notes to get louder or softer.

This is a crescendo: 


This is a decrescendo looks like this:


In a piece of music, they can be put together and look like this:

Music_hairpins crescendo decrescendo
From https://simple.wikipedia.org/wiki/Dynamics_(music)

Here are links to ideas for teaching dynamics:

11/19/15 Dynamics and The Growing Pumpkin Game

12/11/15 Scales and Dynamics (Using Deck the Halls)

(Note: This book is in your resource box.)

1/16 Dynamics, Tempo, Rhythm (Using Stopping By the Woods)

(Note: This book is in your resource box.)

Other lesson plan links:

Making Music Fun: Boom Chicka Boom