Is math by hand better than math by keyboard?

Sorting books this afternoon, I came across Tahir Yaqoob's What Can I Do to Help My Child with Math When I Don't Know Any Myself? and found this passage:

The actual process of using your muscles to write something is a powerful long-term memory aid. The more that you write out things (and in different ways), the more your long-term memory will be etched out. It is not good enough simply to read and think (although this is important for reviewing large amounts of material shortly before taking an exam, but only if you have done the long-term ground work). Writing out full solutions to problems in math is especially important compared to other subjects, whether it is part of reviewing for exams or whether you are learning new material.

Writing things out can also help you to understand difficult problems. For example, if you see a fully worked solution to a problem in a textbook, but don't understand one or more of the steps, try simply writing out the solution yourself. You may be surprised that while you are doing that, you suddenly understand something that you didn't before. Sometimes the brain has a strange way of working. Despite its enormous capacity , the. brain can really benefit from an external "scratch pad." When you come across something that you don't understand, sometimes just writing out the steps in a brief form can make a great deal of difference.

What Can I Do to Help My Child with Math When I Don't Know Any Myself? Paperback – February 7, 2011 by Tahir Yaqoob - p133

I've always found this to be true, both for C. and for me. I don't know why. One of these days I'll get around to reading The Hand: How Its Use Shapes the Brain, Language, and Human Culture, which I hope will explain the phenomenon.

The OECD report on students and technology (Students, Computers and Learning: Making the Connection) found that using the computer for drill was associated with reduced achievement:

The decline in performance associated with greater frequency of certain activities, such as chatting on line at school and practicing and drilling, is particularly large (Figure 6.6). Students who frequently engage in these activities may be missing out on other more effective learning activities. Students who never or only very rarely engage in these activities have the highest performance.

Given my experience, the "other more effective learning activities" these students are missing may be drilling by hand.