There are many solutions to a problem like this. As said in the previous post, a teacher who has not developed their own in-tune singing can probably speak – therefore they can chant – therefore they can access and teach rhythms. Wow! That’s half of music teaching already – so there’s no reason to shy off! If you really struggle to sing in front of your class, compensate by making your practical rhythm work the best you can – SO much can be accomplished with pulse and rhythm work alone.
One way for your children to access in-tune singing teaching if you feel you can’t, is for another teacher to teach your class the songs initially and for your musically able children to pick up on them and be the teachers under your direction for these activities. Also there is so much simple RECORDING EQUIPMENT around these days to use in the classroom so you can RECORD another teacher initially teaching you a song or another class singing the same song and this can be used as a prompt for your musically able children before they lead or for your children to sing along to until they know it. Though it is IDEAL for the in-tune element of the lesson to come from you as the teacher, it doesn’t HAVE to – therefore, all this music teaching is possible, even for non-specialists.
Another option is for the ACTIVE MUSIC DVDs to be played on your interactive whiteboard for the children to sing along to – I know many schools who do this – in both lessons and assemblies. Once the children have had enough prompting in this way, they will be able to sing these songs and play these games independently – which is the idea!