Recent advancement of neurosciences informs the way our brains develop especially from birth to age of five. The chart below shows the neural connections for different functions of human brain to develop in a sequence than concurrently.

Neurons to Neighbourhoods, 2000
The evidence is overwhelming that your child’s brain develop its sensory functions first. At this age, eye training exercise to train your child’s visual, and audio for hearing is very important to help form the high number of neural connections for the brain.
This becomes the foundation for language and communication development where flash cards would usually be introduced to encourage stress-free learning.
That is the reason we only formally begin right brain exercises for memory and higher cognitive function at the age of 3 or 4. Giving your child the best start in life is not by learning about higher cognitive function but by meeting the needs of the brains as it develops. Let children play!