Pause for the child to repeat it. On the back of the form, note to what extent the changes that the child made to the original sentence retained or changed its meaning. I find 'Repeat my Sentence' useful as an assessment tool. The exercise is purely mechanical with poorer students - involving repetition of words without meaning. Higher level students interpret the meaning and repeat it back, but not necessarily using the same words.
Students substitute their own words when sentences become more complex.
One of the ways I use the information gained from this assessment is to decide upon what level of instructions a child will need - for example, a child who jumbled most of the sentences requires short instructions, slowly given, and many repetitions. Some children may add words while retaining the overall meaning. The examples that follow show the sentence the child was asked to repeat followed by what the child actually said and an interpretation of the child's response. My sister reads a lot of books and sometimes she read magazines. My sister reads a lots a books and sometimes she reads magazines.