PM Sounds in Words Set 1 Big Book + IWB DVD - Short Vowels in a Medial Position reinforces and extends what has been learnt with the Little Books. Focus sounds are repeated and then shown within a sentence from a well-known PM book, allowing the children to learn about sounds withing a meaningful context. It is recommended that this series is introduced to students who are reading at PM Level 3 and have acquired a confident knowledge of the alphabet.