Check out this passage from Multimedia Learning by Richard Mayer:
Lightning can be defined as the discharge of electricity resulting from the difference in electrical charges between the cloud and the ground.
When the surface of the earth is warm, moist air near the earth’s surface becomes heated and rises rapidly, producing an updraft. As the air in these updrafts cools, water vapor condenses into water droplets and forms a cloud. The cloud’s top extends above the freezing level. At this altitude, the air temperature is well below freezing, so the upper portion of the cloud is composed of tiny ice crystals.
Eventually, the water droplets and ice crystals in the cloud become too large to be suspended by updrafts. As raindrops and ice crystals fall through the cloud, they drag some of the air from the cloud downward, producing downdrafts. The rising and falling air currents within the cloud may cause hailstones to form. When downdrafts strike the ground, they spread out in all directions, producing gusts of cool wind people feel just before the start of the rain.
Within the cloud, the moving air causes electrical charges to build, although scientists do not fully understand how it occurs. Most believe that the charge results from the collision of the cloud’s light, rising water droplets and tiny pieces of ice against hail and other heavier, falling particles. The negatively charged particles fall to the bottom of the cloud, and most of the positively charged particles rise to the top.
The first stroke of a cloud-to-ground lightning flash is started by a stepped leader. Many scientists believe that it is triggered by a spark between the areas of positive and negative charges within the cloud. A stepped leader moves downward in steps, each of which is about 50 yards long, and lasts for about 1 millionth of a second. It pauses between steps for about 50 millionths of a second.
As the stepped leader nears the ground, positively charged upward-moving leaders travel up from such objects as trees and buildings, to meet the negative charges. Usually, the upward-moving leader from the tallest object is the first to meet the stepped leader and complete a path between cloud and earth. The two leaders generally meet about 165 feet above the ground. Negatively charged particles then rush from the cloud to the ground along the path created by the leaders. It is not very bright and usually has many branches.
As the stepped leader nears the ground, it induces an opposite charge, so positively charged particles from the ground rush upward along the same path. This upward motion of the current is the return stroke and it reaches the cloud in about 70 microseconds. The return stroke produces the bright light that people notice in a flash of lightning, but the current moves so quickly that its upward motion cannot be perceived. The lightning flash usually consists of an electrical potential of hundreds of millions of volts. The air along the lightning channel is heated briefly to a very high temperature. Such intense heating causes the air to expand explosively, producing a sound wave we call thunder.
Multimedia Learning by Richard Mayer, Page 72
If you are like many learners, chances are you didn’t get much out of the text. In Mayer’s research, subjects who read this passage test very poorly (both in retention and in transfer) even if tested immediately after reading the passage. Most people reading this passage probably have a few college degrees, yet sensemaking was probably very challenging for the majority of readers.
Now imagine being a student in their first semester at college. With a handful of other classes. And living away from home for the first time. And worrying about a job. And money. And a car. All of a sudden, the above passage seems even harder to decipher.
Mayer makes the case for different multimedia for different learning outcomes. And after reading the above passage, it is clear that text alone is not the best method of knowledge transfer.
The book starts off as a learning sciences textbook. Want to know about dual channel theory? Are you interested in the science of instruction? Then read the first few chapters. Mayer then turns to research-based methods of effective multimedia that span the gap between theory and praxis.
In the world of online learning (and remote learning, synchronous learning, asynchronous learning, hyflex learning, and hybrid learning), it is critically important to design educational experiences that are engaging, effective, and stimulating. Leveraging effective multimedia is mission critical in this endeavor (though effective multimedia is a very difficult craft to master).
Mayer discusses a number of different multimedia instruction methods and provides cognitive breakdowns and best-practices for each:
- Annotated illustrations
- Annotated slideshow
- Narrated slideshow
- Narrated animation
- Annotated animation
- Animation with pedagogical agents
- Instructional video
- Simulation game
- Virtual reality
Read the book if you’re interested in learning how best to leverage multimedia for your learners.
And check out this video for a brilliant example of multimedia. Targeted at doctors, the video uses humor, wonderful visual aids, a scaffolded approach to content delivery, an approachable tone, and point-in-time learning (based on the vocabulary and references to previous knowledge). Dr. Weaver (disclaimer: I was his camp counselor decades ago) has created a short, engaging, effective, and stimulating learning experience for his students.
If you have not yet picked up the book, you totally should. Multimedia by Richard Mayer.
Image by Gerd Altmann from Pixabay
