in the middle of the words:      something ... nothing ... healthy

                      at the end of the words:           math ... mouth ... both

                      used in sentences:  I will eat anything healthy with my teeth.

                                                    .  Thank you for driving back and forth this month.

                                                   .   I think Beth is travelling north on the path.

Voiced   / ð/  at the beginning of the words:  there ... that ... the

                     in the middle of the words:        brother ... either ... other

                     at the end of the words:             smooth ... breathe

                     used in sentences: That mother can't breathe.

                                                       I rather like this weather.

Voiceless /θ/ and voiced /ð/ used in a paragraph:

Pronunciation is rather fun! If you try another technique, think about the person you are talking with. Although you are pretending this method will make your speaking more smooth. That's all for now!  

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Tongue twisters:     

http://englishwordoftheday2010.blogspot.com/2013/06/th-sound-tongue-twisters.html