Children who are up to these Readers are often able to read simple fictional works, for instance Choose Your Own Adventure stories and the like. This is a great thrill for them.
At advanced levels, Readers occasionally teach up to three new sounds. This speeds up learning without overburdening the now competent reader.
Due to the systematic structure of the program, even more complex sentences are soon no problem.
Notice how the special (i.e. sight) words work together with the spelling patterns learned. Together they help form a base from which children can 'decode' huge numbers of words - even ones they have never seen before.