One child used his personal experiences with sheets on the clothesline to supply meaning in a hymn. It is best to pick some songs which your children know well. Select songs which have words which you want them to learn. They already know how the words are used in familiar songs. They can associate this with learning the definitions.
Repetition is enjoyable when they are singing.
Introduce the lesson as an easy and enjoyable way to learn new words. On your copy of the song, underline words which you want to teach. If you make copies, be careful about the copyright law. Media specialists and librarians can offer advice. Let the children sing one song.