teaching this lesson, it will be useful to refer to the
Pages before you begin, to give you vital information
associated with the unit. You will need an Authorware Web Player
plug-in for the Activity and Test Your Knowledge sections.
If your computer does not have the plug-in, Click
here for the plug-in.
One of the
ways we encounter environmental hazards is through the food we eat.
or organisms in or on our food and water enter the digestive system
and may cause serious problems throughout the body.
In this lesson
you will learn about substances (such as food additives and chemicals),
and organisms (such as bacteria and viruses), and the problems they
can cause in the body.
So who are
Sam and Ella? You'll find out if you read the lesson carefully.