Dual coding is a scientific way to say that learning through a combination of reading, listening, and/or looking at images or videos makes a stronger learning that any of those on their own. This can include finding various types of information and using your memory to create a picture or diagram from something you read.
Look at your class materials and find visuals. Look over the visuals and compare to the words.
Look at visuals, and explain in your own words what they mean.
Take information that you are trying to learn, and draw visuals to go along with it.
Note:
Try to come up with different ways to represent the information visually, for example an infographic, a timeline, a cartoon strip, or a diagram of parts that work together.
Work your way up to drawing what you know from memory.