Can I also add that some of words I think are a little too long for a baby, such as rhinoceros. In my opinion either shorten it to rhino or pick another animal. (I even had to type it twice to remember how to spell it)
Doman actually encourages the use of this kind of words because they are more interesting to the child. In the long term you child probably will not have to type it twice because the word is register in his brain
That may be one of the easiet words for him to spell. This is the beauty of this, our kids are going to do so much better than us...