Gua Sha, known as kerik in Indonesia, Cao Gio in Vietnam (see Harvey Keitel's The Three Seasons) and khoud lam in Laos is a legitimate and effective therapy. In Asia it is usually done with a coin, Chinese soup spoon, slice of water buffalo horn, or even a slice of ginger. A simple cap with a rounded edge is quite good to use and available in most homes in the West. It was not commonly done with wood, but if smooth and the right edge it could be. There is a teaching text in English called Gua Sha. A Traditional Technique for Modern Practice, and a teaching video: Gua Sha: Step-by-Step, by Arya Nielsen.If an acupuncturist is trained in Classical Chinese medicine, they will do this technique in their practice for pain, and for acute or chronic illness.
Gua Sha is a treatment in traditional oriental medicine in which a wooden board repeatedly slides across the patient's acupuncture/acupressure/massage points. It works in similar principles like that of acupuncture/acupressure/massage. This method would inevitably leave bruise on the skin, and the story begins here, when the visiting grandpa who does not speak any English used this traditional practice to treat the grandson when both son and daughter-in-law were at work.
Sadly, in US, this is a story that repeats itself many times in the area where many oriental immigrants lives and all of these are due to simple misunderstanding between cultures.
Gua Sha (The Treatment) shows how a person's cultural beliefs are so deeply set within oneself that it is usually impossible to examine why you do most anything, from how you dress and talk to whom you love and respect and how you show it. The invisible nature of one's cultural beliefs also makes it difficult to impossible to explain yourself to others when questioned. Da Tong experiences an excruciatingly painful and difficult struggle while trying to protect his son, an ordeal that forces him to examine the validity of some of the most vital things he thought he knew about his identity, his Chinese culture, and the new American world he'd chosen as his home.
The movie showed me how normal it is for people to look for ways that their culture is superior to others' and how the misunderstandings arising from different cultural perspectives can seem very large, but can be nullified with simple, 2-sided explanations when people are willing to listen.
It appears this film is not readily available in the USA, but it's the best I've seen at highlighting the differences between American and Chinese culture. Parts of the movie's dialog are only in Chinese and I've yet to find a DVD with English subtitles, although it's easy to get the gist of what's going on during those short passages. The credits are a combination of Chinese and English, holding true to the integration of both worlds. I've noticed some important roles are not credited here on IMDb, such as Judge Horowitz, who was played by Alexander Barton.