Unit 4 provides strategies for effectively teaching students the 300 most frequency occurring words. Although many of these words can be encoded with a basic phonic knowledge, there are quite a few words which require advanced skills. The current research shows the importance of helping students identify the phonemes (sounds) in each word and making links between each phoneme and the grapheme (letter or letter combinations) representing that phoneme and this is an important part of the process. However, in addition strategies from the memory research are also incorporated into helping students learn words containing more complicated graphemes.