Eliminate noise and other distractions that cause the child to lose focus. Seat the child away from a window and put him at the front of the classroom so he can't be distracted by the students who are sitting around him.
Incorporate movement into lessons whenever possible. Children who are easily distracted will be more focused if they don't feel the temptation to move around. Satisfying this need will allow her to concentrate more on each lesson.
Take note of the most pertinent information. Write the information in large, clear letters and in simple language so that the child can easily understand. Repeat the main ideas until you think the child understands.
Make the lessons as easy and fun for the child to learn as possible. Large concepts can be broken down into sections so that the child can learn them individually and then apply them to the larger concept. He will more easily concentrate on an understandable concept rather than one that is overwhelming.
Let your child have breaks. Many students start out by concentrating but become restless and need to move around. Children have much more energy than adults and need the means by which to expend that energy.
Ask the child the occasional question to ensure she is paying attention. If she anticipates that you will ask her a question, she will be more eager to listen.
Ask the class for complete silence and for their full attention before starting a lesson. Children may not notice they aren't paying complete attention, but letting them know that they need to be quiet will help them focus.