Multimedia principle:
People learn better from words and pictures than from words alone.

Which of these two examples do you think gives you the information you need?
Which is better for learning?
Are they doing the same job?
What is the target audience for each?
http://amasci.com/amateur/trshort.html

http://www.learnabout-electronics.org/bipolar_junction_transistors_04.php

Contiguity principle:
People learn better when corresponding words and pictures are presented near rather than far from each other in time or on the screen.

Here's an example of a technical diagram with appropriate labels. The descriptive text is also close by; Aha but a snag! try the translation gadget offered (bottom left) and see what happens to the diagram labels...... Click the link. Can you think of a solution?
http://www.learnabout-electronics.org/ssr_01.php

Coherence Principle:
People learn better when extraneous words, pictures, and sounds are excluded rather than included.

For our younger viewers? How Stuff Works is a popular learning site. Here we look at the topic area of transistors again. Do you think Mayer's Coherence principle could be applied here?
Maybe you would like to choose a short video to explain the transistor topic more fully?
Maybe you're just bored and would like to surf around?
You may still be learning - but what was it we came here for?

Modality Principle:
People learn better from words and pictures when words are spoken, rather than printed.

Here's an example from Adobe .com.
When does entertaining become annoying?
How many times will you need to view the video before you can remember all the steps?
Better that boring old lists of instructions?
Instructions better 'cos you can print them out?
Click comments to praise or pan adobe!

Redundancy Principle:
People learn better from animation and narration than from animation, narration and on screen text.
Animations are great for learning. Here's an example (yes a transistor again) that the learner can play with - its interactive.

According to principle 5 it would be improved if the instructions were spoken.
Is that possible with an interactive animation such as this?
What would happen as you advance the slider and the instructions change?
Is it helpful to have a written explanation to look at as you try different parts of the animation?
Just how would you apply principle 5 to this example?

Personalization Principle:
People learn better when words are presented in a conversational style, rather than formal style.

What is your "Conversational" style?
So how do you like your stuff shoving at you dude?
Do you think casual's best?
Do you prefer your personal learning materials to be offered in a more formal manner?
More formal more accurate? More informative?

Well this is one principle I'd like to modify. How about:
People learn better when words are presented in a language that is suited to the expected audience?

Can you use "Formal" language and still be fun?
Try a page or two from the University of Texas' site for French Language learners.

Voice Principle:
People learn better when words are spoken in a non-accented human voice than in a machine voice or accented voice.

Seems that the question of accent is dependent on who the listener is. Non-accented to one user is quite likely to be accented to another.

Of course there is always "Received pronunciation" (RP) but how does that fit with the conversational style required by principle 6?
Again - who is your target audience?

Signaling Principle:
People learn better when the voice signals important words rather than when there are no signals.

Sounds can be helpful.
Sounds can be Fun.
Sounds can highlight important stuff
Sounds can be lethal
When sounds annoy
And learners say
That's enough!

Interactivity Principle:
People learn better when they can control the pace of presentation than when they receive continuous presentation.

Too much to take in? Let learners set the pace by using short sections, pages that they dont have to scroll through but can read one one (or not much more) screen.
Use short videos and sound clips.
Use animations the user can control.

Pretraining principle:
People learn better when they receive pretraining on each component rather than no pretraining.
What's it all about. We learn more effectively when we know what we should be learning.

Without effective pre-training it's like being lost and on asking the way, being told, "Well if I'd have been going there, I wouldn't have started from here!"