The Shape and Structure of DNA

This week, we learned about the shape, structure, and purpose of DNA in our bodies. We started from scratch, by asking the kids to draw or write anything they knew about DNA. We got some varied answers – some of the kids said “it’s your blood”, while others knew the exact structure of the double helix. After finding out what they knew, we taught the kids more about DNA and the double helix, as well as the nucleotides that are paired on a strand of DNA. The kids put together their own nucleotide pairings using the four colors of Sour Patch Kids to represent the four nucleotides, then attached their creations to some Twizzlers and made their own double helices! Watch the slideshow to see the kids showing off their creations!

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Polyurethane Shakes and Slime!

This lesson provided a very hands-on experience with chemical properties! The kids got to make their own polyurethane foam “milkshake”, and then they created some slime to take home!

The polyurethane foam we used was the same as the mixture that is used for insulation in homes. We added different colors of food coloring to make it more exciting, let the kids mix the two solutions (which come together to eventually form a hard polystyrene), put our straws in, and then we all just sat back and watched! The foam expanded and grew out of the cups before the kids’ eyes. After about 10 minutes, the foam was completely hard and no longer dangerous to the touch, and the kids could take their “milkshakes” home to their parents!

 

Next, we created a special slime mixture using polyvinyl alcohol and borax. After adding the two solutions together (along with some fun colors), the kids stirred for about 30 seconds; they were amazed to see that the two liquids had formed a slimy blob! Another fun chemistry experiment that they could take home with them!

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The People of ScienceDays

Here are just a few of the mentors and children who made ScienceDays such a great experience this year!

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Cow Eye Dissection!

We ended the 2010-2011 school year with the cow eye dissecti0n – one of the most fun and interesting (and sometimes gross!) lessons of the year. Each mentor led several children through the steps of the dissection, with the ultimate goal being to find the lens of the eye.

We removed the sclera, or the outer covering, and the cloudy cornea, to see the muscles of the eye. It was interesting to learn that although cows have a very wide field of vision, their eye can only move in four directions – up, down, left, and right. Cows can’t roll their eyes like humans!

After cutting through the cornea, we reached the back half of the eye and found the pupil, the iris, and the shiny lens of the eye!

Check out pictures from this year’s dissection – but be warned if you’re squeamish!

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Reference: http://www.exploratorium.edu/learning_studio/cow_eye/index.html

Tower Building!

Elementary school students learned about physics and architecture through building towers from various materials. Older students were challenged to build the tallest tower they could, using ONLY newspaper and tape! The kids were successful in building a tower that was taller than they were. They learned that pleating or rolling paper can help to increase its stiffness and sturdiness. (http://www.pbs.org/wgbh/buildingbig/educator/act_tower_ei.html)

Younger students explored the laws of physics on a smaller scale – they built structures using only gumdrops and toothpicks. Some tried to build the tallest tower, but others just built a sturdy house! These students learned about shapes that would make their structures strong – for example, triangular walls held up much better than square ones did.

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Static Electricity and Lightning!

Look at the balloons!  This was the first week of ScienceDays tutoring here at Duke University.  This week, we taught at two local elementary schools, George Watts and EK Powe  (Durham Public Schools) at their after school programs!  Our lesson this week was about static electricity and how we can use everyday objects to demonstrate common experiences such as the shock you experience when you walk across carpet.  We were able to charge these Valentine’s Day balloons with our hair and we also played with combs to demonstrate the polarity of water.  Lightning is a dramatic demonstration of static electricity that we occasionally see.

From wikipedia:

“The static charge in air typically breaks down in this way at around 10,000 volts-per-centimeter (30 kV/cm) depending on humidity. The discharge superheats the surrounding air causing the bright flash, and produces a shock wave causing the clicking sound. The lightning bolt is simply a scaled up version of the sparks seen in more domestic occurrences of static discharge. The flash occurs because the air in the discharge channel is heated to such a high temperature that it emits light by incandescence. The clap of thunder is the result of the shock wave created as the superheated air expands explosively.”

So that is a cool example of how static electricity can affect our everyday lives!  For all who are interested, our lesson plans for this week are posted online at:

http://sciencedays.org/curriculum/lessons.html.

Cheers and welcome to our blog!

Goo Lesson and Quicksand

Yuck! Look at that goo! At this lesson, we made homemade goo using corn starch and water!  Just mix the two of them together with some food coloring and we get tons of icky goo!  We used this lesson to demonstrate the properties of quicksand, a type of sand that is commonly found near riverbeds, lakes, and other watery habitats.  What is quicksand?? Wikipedia says:

Water circulation underground can focus in an area with the optimal mixture of fine sands and other materials such as clay. The water moves up and then down slowly in a convection-like manner throughout a column of sand, and the sand remains a generally solid mass. This lubricates the sand particles and renders them unable to support significant weight, since they move with little friction, behaving more like a liquid when exposed to stress. Since water does not usually go up to the surface of the sand, the sand on top appears solid, and can support leaves and other small debris, making quicksand difficult to distinguish from the surrounding environment.

Do you know how to get out of quicksand???  Well first, stop moving around and then try to lay down on the sand.  As you lay down, you will increase the surface area that your body is in contact with the sand.  Then, try to slowly crawl out.  Watch Bear Grylls get out of the sand!

For all who are interested, our lesson plans for this week are posted online at:

http://sciencedays.org/curriculum/lessons.html.

Cheers!