my nine year old asked what cancer is.  can you give me a simple
explaination, what might include pictures or a video clip

Hi! Thanks for the question.

I found this animation explaining cancer from Brainpop.com

BrainPop: Cancer
http://www.brainpop.com/health/diseases/cancer/index.weml?&tried_cookie=true

Here are other websites that explains the concept of cancer to children.

Kidshealth: "What is cancer?"
http://kidshealth.org/kid/health_problems/cancer/cancer.html

Kidshealth: "Finding Out About Cancer"
http://kidshealth.org/kid/health_problems/cancer/cancer_p2.html

"When Someone in Your Family Has Cancer"
http://www.nci.nih.gov/cancerinfo/when-someone-in-your-family/page1

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"what is cancer" kids        
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Easterangel-ga             
Google Answers Researcher

Angel, this is a terrific answer!

I was diagnosed with skin cancer last summer, and had to explain what
cancer was to my boys before I went in for surgery.  They were just 10
and 6 at the time.  One of the resources I used was the BrainPop site,
which is factual, yet non-alarming.  It was reassuring to them, they
were far less nervous when I had my surgery.

-- Missy

thanks so much for that comment

Hi!

I would like to add one more site for its nice graphics and
easy-to-follow content.
I have used the site for my school assignment on cancer basics. 

"Understanding Cancer" from the National Cancer Institute
http://press2.nci.nih.gov/sciencebehind/cancer/cancer01.htm

You just need to click on "next" button on the left to proceed.

Hope that helps.