The hydra of spelling!
http://literacyblog.blogspot.co.uk/2013 ... use-i.html
As one dad to another, your attitude towards your daughters seems exemplary. The sentence ‘a see cretur finds a shel’ is the kind of spelling any YR/beginning of Y1 teacher would be proud of. However, as you say, you wouldn’t be very happy if your daughters were in Y11 and still spelling like that. Leaving aside the issue of the grammar (children know something like around two-thirds of the grammar of the language by age 5), you are quite right in thinking that they will be subject to various approaches to the teaching of spelling as they progress through school. This is because, in the main, most primary teachers don’t understand the spelling system and how it relates to the sounds of the language.