On the Shoulders of GiantsScience Demos in Division 3 & 4

Michelle StevensEdmonton Public

Michelle.stevens@epsb.ca

If I have seen further it is by standing on the shoulders of giants.

Isaac Newton

"One who develops future intellectual pursuits by understanding and building on the research and works created by notable thinkers of the past".

Strawberry DNA extraction Concepts covered: DNA Curriculum connection:

Science 9 A3.1K Science 24 C4.5K Science 30 A3.4K Biology 30-C3.1K and

C3.2K

Procedure:1. Chill the rubbing alcohol in the freezer. (You'll need it later.)2. Mix the salt, water, and Dawn detergent in a glass or small bowl. Set

the mixture aside. This is your extraction liquid.3. Line the funnel with the cheesecloth, and put the funnel's tube into

the glass.4. Put the strawberries in the plastic bag and push out all the extra air.

Seal it tightly.5. With your fingers, squeeze and smash the strawberry mixture for 2

minutes.6. Add 3 tablespoons of the extraction liquid you made in Step 2 to the

strawberries in the bag. Push out all the extra air and reseal the bag. The liquid detergent will help break the strawberry cells open allowing the DNA to spill out. The salt helps create an environment where the different strands of DNA can gather together in a clump making it easier for you to see them.

7. Squeeze the strawberry mixture with your fingers for 1 minute.8. Pour the strawberry mixture from the bag into the funnel. Let it drip

into the glass until there is no liquid left in the funnel.9. Throw away the cheesecloth and the strawberry pulp inside. Pour the

contents of the glass into the test tube or small glass jar so it is 1/4 full.

10. Tilt the test tube or jar and very slowly pour the cold rubbing alcohol down the side. The alcohol should form a layer on top of the strawberry liquid. (Don't let the alcohol and strawberry liquid mix. The DNA collects between the two layers!) DNA does not dissolve in alcohol. When alcohol is added to the mixture, the rest of the mixture, except for the DNA, stays in solution, while the DNA precipitates out into the alcohol layer—that’s the gooey clear/white stuff you can collect with a skewer or other thin rod.

11. Dip the bamboo skewer into the test tube where the alcohol and strawberry layers meet. Pull up the skewer. The whitish, stringy stuff is DNA containing strawberry genes!

Why do Demo’s? Demonstrate

Sometimes words can’t explain it

Now You See It, Now You Don’t Concepts covered: Inference Curriculum connection:

Any science as STS and Attitudes

Why do Demo’s? Demonstrate

Sometimes words can’t explain it Learning Objectives

Especially STS! Encourage Discussions and Questioning

often once they’ve seen something, they ask for more

Floating Crayon Demo Concepts covered: Curriculum connection:

Science 8 A3.4K (specific) Science 14?

Why do Demo’s? Demonstrate

Sometimes words can’t explain it Learning Objectives

Especially STS! Encourage Discussions and Questioning

often once they’ve seen something, they ask for more Preparation and Practice

May also help other students (hearing impaired, for example) Focus student attention

Hook ‘em! Nothing like a little science magic to get a kids attention

Water to grape juice to Pepto-Bismol Concepts covered: indicators, acid base,

chemical/physical change Curriculum connection:

Science 8 A3.4K Science 9 B1.1-3K Science 14 A1.5K and A2.7K Biology 20 A2.2K Chemistry 20 C2K Science 24 A2.3K Chemistry 30 D1.3K Science 30B1.4K

Best reason why to do labs and demos?

Because they are FUN!

Oobleck lab Concepts covered:

non-newtonian, states of matter, particle theory Curriculum connection:

Science 7 2.3K Science 8 A3.4K Science 14 A1.6K Chemistry 20 A 2.7K Science 24 A2.3K

Things you should note… Visibility

Can they see it? Repetition

Did they get it the first time or did you rock their world? They may need to see it again to believe it.

Showmanship “Anyone, anyone?”

Explanation Sometimes they need it spelled out for them.

Vanishing Test Tubes Concepts covered: density, light Curriculum connection:

Science 8 A3.3K and C1.1K

Things you should note… Summarize

Repeat, repeat, repeat Cope with failure

Let’s face it, even the best demo sometimes lets us down

Safety Doing first aid is never fun.

Some barriers… Knowledge Access

Do you have this chemical or can you have it??? Safety Time

Videos to Show Demos BAD, but do you know why???

http://www.youtube.com/watch?v=m55kgyApYrY

Not so great http://www.youtube.com/watch?v=igSE5_Nce28

Good http://www.youtube.com/watch?v=hKoB0MHVBvM http://www.youtube.com/watch?feature=player_em

bedded&v=wrq6wjh2Db0 A fav for chemistry videos:

http://www.periodicvideos.com/videos/055.htm

references http://alomshaha.com/2012/04/the-use-of-demon

strations-in-science-teaching.html http://www.beyondstrengthperformance.com/wp-

content/uploads/2012/05/2011-10-10-ShouldersOfGiantsFINAL.jpg

http://chemistry.about.com/od/chemistryhowtoguide/ht/oobleck.htm

http://en.wikipedia.org/wiki/Standing_on_the_shoulders_of_giants

http://www.sciencebuddies.org/science-fair-projects/project_ideas/BioChem_p015.shtml#procedure