In addition to being taught to decode words, research suggests that students benefit from being taught to instantly recognise the most common words in English, especially those with irregular spellings such as 'who' and 'said'. Learning to instantly recognise highly frequent and irregularly spelled words helps students to develop fluency in reading.  

Please note: teaching students sight words before they have learnt basic decoding skills is NOT recommended, and not supported by research! Teaching sight words should be a complementary strategy to assist the development of fluency as part of a systematic, phonics based method of reading instruction.