How fast should flash cards be shown?
There are two schools of thought on this.
In doing so, the information you present to your child will be absorbed unconsciously by the right hemisphere of her brain. Learning is effortless and extremely rapid. When children are below the age of three and a half, it is very easy for the brain to apprehend information in this way.
For older children, it may be necessary to precede the teaching session with a period of relaxation and guided visualization. Such exercises are very effective at activating the right brain through the achievement of the alpha wave state (deeply relaxed yet fully alert and aware), which is very similar to the state achieved during deep meditation.
For more on this, go to Right-Brain Learning.
The second way of showing flash cards is to use the multisensory method. The philosophy here is that it is easier for children to absorb and retain new information when they receive that information through several sensory channels. This means that rather than simply reading aloud a word to your child (as you flash that word card), you would read aloud the word and follow the word card with a picture card representing the meaning of the word. Software programs such as Little Reader contain recordings of words to be taught, plus sound effects - e.g. the sound of an elephant trumpeting to go with the word "elephant." Another advantage to this technique is that it teaches children the meanings of words, rather than simply their pronunciations.
Multisensory learning is also considered a right-brain teaching technique, because it works partly on an unconscious level. Multisensory teaching has been known to be extremely beneficial for children who do not respond well to traditional, left-brain teaching. Besides the visual and auditory modes of stimulation, multisensory learning also encompasses the kinesthetic - that is, moving your child's body to model the meaning of a word, or encouraging him to do so, when he is old enough to move by himself. So, for example, you might raise your child's arms in the air, or both of you might raise your arms in the air while reading the words "Arms up!"