presentation?

Question

a group of college students have to do a presentation on chemistry or biology for 7th graders. does anyone have any suggestions? I need to implement why that is that way or this way and why.

Answer 1

I have done a "chemical magic" show for that age group several times. They love it. But I try to convey a little scientific knowledge at the same time. I use the theme "what is a chemical reaction?". For example I tell them that a chemical reaction always produces a new substance, and sometimes that new substance can undergo an additional reaction. To illustrate, I dump three beakers of clear liquid into a larger beaker, then hold it up where they can see it clearly. After about 5-8 seconds the solution instantly turns bright orange, and everyone oooh's and ahhh's, then after another 5-8 seconds it instantly turns jet black (additional oooh's and ahhh's).

Then I explain that one substance can react with several other substances to produce different products. I take my "magic pitcher" and pour it into a series of small beakers, where it turns into milk in one beaker, coke in the next, coffee, orange juice, wine, etc.

Then the idea that the reaction produce can also be a gas. I ask them how we might tell if a gas is being produced. Make them think a little. Then drop a seashell into a 2000 ml graduated cylinder with an acid solution in it, and let them see the bubbles streaming up as the shell is turned into CO2.

I have about a half dozen other simple demonstrations, each teaching something about the nature of reactions. It really holds their interest. At that age you have to have something WOW or they just are not interested.

Answer 2

Maybe something they've seen on TV....like crime scene investigation. Talk to them about PCR and DNA sequencing used to catch criminals. In that talk you could explain what controls are and why they're important in this real life application.