Children do need to learn to figure in their heads and to do paper and pencil work, but these methods alone will not meet contemporary needs. Aversion to using calculators in schools contrasts with their general acceptance in the work place and the daily life of adults. If schools do not teach students to use these devices from an early age, the rising generation will lack necessary work skills. Calculators are one tool almost every employer expects employees to use. Calculators are ubiquitous in the work world and as important for employees as voice mail and word processing.
Word processing is an analogous skill.
We do not require that students check all spelling with a dictionary rather than by the computer's spell check program. Instead, we expect students to be able to gauge the reasonableness of a spell check message using their own experiences drawn from reading, writing, and dictionary use. In the same way, young students can learn to compare the calculator's messages to the reasonable answers they have learned to expect from their evolving understanding of arithmetic. The issue is not should students use calculators in the classroom but how calculators should be used. When students do not have to worry about computation mistakes, they can focus on reasoning and problem solving.