“Mary Poppins” showman posted a video on Instagram showing himself and a friend as he embarks on his “first ukulele lesson” from instructor Melanie Kareem. Strumming along, Van Dyke is seen asking his teacher, “Where’s the F?”“It’s never too late to start something new,” he captioned the video.The Post has contacted Van Dyke for comment. Fans praised the Tony, Grammy, and Emmy-winning icon in the comment section for providing “a lesson on how to stay young.”“Amen! I started tap dancing at age 60.