Proponents of teaching manuscript writing to elementary students before cursive penmanship point out that books are written in printed type. The child may be confused as to why the material he is reading contains a style of letters that is different from that which he is reading. This may delay the the child's ability to read because he is trying to decipher a format he is not familiar with. Teaching printing first reinforces consistency between what the child writes and what he reads.
Printing, as a whole, is easier to write than cursive. With cursive, the child learns to make more difficult strokes. As a result, it may take him longer to learn to write and complete words legibly.
In some ways, writing in manuscript type is easier to teach than cursive. Many teachers use a "movable" alphabet to allow students to create words, in which individual letters can be combined. The movable alphabet in cursive, however, has letters that do not connect together, even though they are in a cursive style. This "imposter" form of cursive can confuse a child learning to read. Printed letters in a movable alphabet can be joined together and appear the same way as the child writes them.
Cursive is generally less legible as a form of writing, which is why nearly all forms indicate that they should be filled out with printed letters. Writing with manuscript penmanship is a skill that is both easier to learn and will be required of the child in life.