Test 1
The exercises are numbered in a way that corresponds to the packet. For instance, exercise 1.3 is related to the material on packet page 1.3.
When you have completed an exercise use the back button in your browser to return to this page. (I have discovered that the back button does not work very efficiently if you are using Internet Explorer for Windows. In this case it might be better to save this page in your favorites to return to it.)
1.1a Sound, Valid but not Sound, or Invalid