This should never be done. Often when a child is forced to use a different hand than his or her dominant one this can affect speech development and other aspects of learning. Right-brained people are usually very good problem solvers and much more creative. Unfortunately, many schools are not ample learning environments for right-brained students. Often they are also very visual, learning better by visual images rather than auditory instruction.
Many schools are unable or unwilling to adapt.
Many times these people are also kinesthetic. This means that they learn better with hands on tools. Labs or other physical projects help these students to learn better. Kinesthetic learners can also be very gifted in physical arts like dance, music, or singing. This means that the left side of your brain is dominant.