Keep in mind that some students use small writing to disguise its messiness or spelling, though. Allow students to use paper or writing instruments of different colors. Allow student to use graph paper for math, or to turn lined paper sideways, to help with lining up columns of numbers. Allow the student to use the writing instrument that is most comfortable. Many students have difficulty writing with ballpoint pens, preferring pencils or pens which have more friction in contact with the paper.
Mechanical pencils are very popular.
Have some fun grips available for everybody, no matter what the grade. Word Processing should be an option for many reasons. Bear in mind that for many of these students, learning to use a word processor will be difficult for the same reasons that handwriting is difficult. There are some keyboarding instructional programs which address the needs of learning disabled students. Consider whether use of speech recognition software will be helpful.