science ideas needed

I am teaching the science lesson on Friday for our co-op. I keep putting off the planning and have no idea what I want to do. What was your favorite science experiment as a child? We will have about 1 hour and the age range tends to be k-5 (with younger siblings tagging along). Any ideas are appreciated.

 

Do you have any Lego or Knex? What about building bridges and then seeing what weight they take before they collapse? Or you could build bridges with other common objects such as paper or cardboard.

 

Mentos and coke?

Iron in cereal?

Anything with baking soda and vinegar?

 

what type of science?

 

Any, we just have "science" on the first Friday of the month.

 

I debated the mentos. I have done all of those with my own son, forgot about the iron in cereal. Thanks.

 

Legos abound at my house , we could definitely do bridges. Thanks!

 

oh, okay, cause we have found a tone of videos on youtube that gave me ideas for science experiments and projects try looking there they show you what you need and how to do it!
http://www.youtube.com/watch?v=CsJBo6yXaUs