Sit down with the child down to determine what he is studying in school. Read his school materials and try to assess how well he is understanding and retaining new words.
Make a list of words that the child is struggling with.
Create flash cards using the words from your list. On one side write the word in big letters. On the back add the definition.
Add more words to the deck that the child has not yet covered but that are nearly on the same level. Try to include words that are challenging but not too difficult. Incorporate new words at regular intervals, such as once a week.
Review the flash cards with the child nightly. Reward her with a day or two off once she has successfully mastered all of the words.
Test your child's memorization by using the words in everyday interactions with the child. Ask him pointed questions that will allow him to demonstrate his understanding.