Week 4 Answer:

Last week Science Spark looked at how flexible you are. We asked you to let us know whether you can touch your elbow with your tongue. The activity was intended for you to explore how your body works, and realise some of its limitations.

Most of us can put one arm over our shoulder and join hands with the other hand behind our back. People who are right-sided will find that it is easier if they put their right arm over the shoulder, whereas, people who are left-sided will find it easier with the left arm over the shoulder. How well you can do this depends on how flexible your shoulder joints are. It gets easier with practice.

On the contrary, most of us will find it impossible to touch our elbow with our tongue. Unlike the arm linked behind your back, this trick cannot be learned through practice. Your shoulder joints can rotate to do the arm link. With practice the shoulder joints become more flexible, so you can rotate your arms back further, making the arm link easier. There are at least three factors that prevent you from touching your elbow with your tongue, the length of your neck, the length of your tongue and the length of your upper arm. As these parts of your body are fixed you cannot change them through practice.

However, there are some people who can touch their tongue to their elbow by dislocating their arm from their shoulder joints. This will shorten the distance between their elbow and their mouth. These people are often known as double-jointed. This does not mean that they have more joints than others, but that their joints allow more extreme movements.

To learn more about how your body works, check out some of these sites:

http://www.bbc.co.uk/science/humanbody/

http://www.geocities.com/thesciencefiles/double/jointed.html

http://amos.indiana.edu/library/scripts/joints.html

http://www.innerbody.com/htm/body.html

http://users.tpg.com.au/users/amcgann/body/

Science of Flexibility
By Michael J. Alter

The WINNER for this week 4 Science Spark Quiz is:

Esther Seow
IC: S8626116B

This is the last of the series of Science Spark quizzes. We hope that you have enjoyed these quizzes and have learned some interesting things about how your body works.