Tinwhistle websites seem to come and go but those listed below are currently free to use with no log-in required.
www.clarketinwhistle.com This link is an excellent website, which introduces a brief history of the whistle and is beautifully narrated by James Galway. There is also a good explanation of the different sounds whistles from various metals will produce. Sound files have been provided so you can hear the difference.
www.whistletutor.com Sean Cunningham has generously provided everything the student should need to become a whistle player on his completely free website.
www.tinwhistletutorials.com Debbie Wilkinson, from Belfast, Northern Ireland, provides a free website with sheet music, mp3 sound clips and tutorials.
www.tradlessons.com Michael Eskin, from San Diego, CA, which provides multimedia whistle instruction from novice to advanced player. The website is free but Michael does provide a PayPal link for donations, should you be so inclined.
www.musicbypatty.com This is my website where I have posted notes from all of my classes. Just go to LESSONS on the right side of the homepage and click on it to produce a drop down menu. Select the appropriate class and print any desired lessons.