There are specific characteristics that define the right-brain learner and set them apart from their left-brained counterparts. Right-brained learners are identified by how they take in information, how they process it, and how they most easily remember what they learn. When we speak of right-brained learning, then, we are referring to what is most natural for them in terms of how they process information.
If your right-brained child is learning the sounds that letters represent, why not jump right in and teach the sounds from within whole sight words? Since they are big-picture thinkers, right-brained learners are most successful when you start at what we'd typically consider to be the end and move toward the beginning.
One factor that exacerbates an already difficult situation is what happens in the brain when stress occurs. If you take a primarily right-brained learner, put her into a logic/sequential educational setting, the result is going to be stress for the child.
While our whole brain is engaged with anything we do - people are primarily Left- or Right-Hemisphere dominant in regards to how they learn. Our school system is structured to work for 15% of children.