Class Demo / Investigation Suggestion
Set up a glass baking dish with water. Drop a pebble. Have class make observations and time how long for the first wave to reach the side of the container. Then use a cornstarch water mixture and repeat the pebble drop.
The YouTube videos and online science simulations in the link below would support this demonstration well.
Have a look at the resources I have posted here: http://stempreacademy.hawaii.edu/subject/earthquakes
Let us know how this goes and if you discover other resources teachers may find useful. Thanks!