While playing word search your mind is actually repeating over and over again the particular word that you are looking for, thus consolidating the word as well as the the spelling to your memory. Retention is also facilitated by the fact that you are not studying but playing, so the words committed have a priority route to the memory centre.
Encounter new words
Learning vocabulary is one of the first steps of learning a second language. Word search puzzles offer the student new vocabulary daily.