Begin blending and reading one vowel words and short. They need systematic instruction that guides them through each phonetic and decoding skill using a step by step logical sequence.
Phonics Literacy Teaching Guide Phonics
Research has found that students that struggle with reading have working memory issuesthus the ability to filter categorize and prioritize information is very difficult for struggling students. Phonics is a method of instruction that teaches students correspondences between graphemes in written language and phonemes in spoken language and how to use these correspondences to read and spell words.
Rather it is a family of phonics instruction that includes the methods of both synthetic phonics and analytical phonics. Systematic and explicit phonics instruction is more effective than non systematic or no phonics instruction.

Systematic Phonics Instruction Findings Of The National Reading