Program a sprite to do something over and over again using a loop.
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Here is the Rubric.
This sprite has two costumes. A face with an open mouth and a face with a closed mouth. The next costume command makes it switch to the next costume. The wait 0.2 seconds looks good to me, you could pick faster or slower. When it changes 18 times, it looks like it's talking. I used trial and error to choose the number 18 so it worked with the text to speech.