Ceramic magnets are made of a brittle material similar to pottery. They can chip, crack, or shatter if they are allowed to slam violently together or drop onto hard concrete floors. Handle them with care during classroom practicals. Keep this set safely away from pacemakers, computer hard drives, credit cards, and sensitive electronic testing meters. Store them stacked neatly in a dry storage box away from strong neodymium magnets to preserve their natural polarity.