These worksheets are great to build students vocabulary and help them decode words and their meanings. Students will learn that the prefix "in" means not and is often changed to match the first letter of the base word which sometimes results in a double letter. The worksheets also permit students to use dictionaries. Students may also choose to look up root words on the computer. Early finishers can create before and after mind pictures of the word and present them to the class. I have found that students really enjoy these worksheets.