Crime Busters B

[iheartscience]

Hey Everyone!
What do you think is essential to learn about DNA?

[Soccer_Girl]

The four bases: Adenine, Thymine, Guanine, Cytosine. Adenine pairs with Thymine, Guanine pairs with Cytosine. That's all I'm aware of...

On a different topic, for fibers, how general/specific are you supposed to be? What are the fibers you have to know? What results are you looking for in the case of a burn test?

[dholdgreve]

There are Event Coordinators out there that may penalize you for being too specific when it comes to fibers... saying "cotton" instead of "vegetable' for example... per the rules, you are to distinguish between vegetable, animal, and synthetic... that's it... The general consensus is that any further differentiation would just be a guess with the equipment provided, which would be in total conflict with the scientific process.

As for defining the three general categories mentioned above, I believe you will be more successful if you hold them well above the flame and watch how each reacts to heat, as opposed to whether or not they burn.... pay special attention to the smoke characteristics of each... I know, everybody in the room is burning something different, how do I know which smell is mine? that is why this should be secondary to the heat reaction.

[ewolf1230]

Thanks--this is completely true. The essay I found is usually about half a page or so, it shouldn't be too long

[dholdgreve]

Thanks--this is completely true. The essay I found is usually about half a page or so, it shouldn't be too long

OK... Let's talk essay... I've been running Crime Busters at various Invitationals here in Ohio for the past 15 years or so... Here is 15 years of collected wisdom in one short paragraph
1) Be organized... One suspect at a time, did he or did he not do it, what evidence points to or away, what motive... then move on to the next suspect.
2) Do not use pronouns - "He," "She," or "It" does not definitively tell me who you are talking about.
3) Be assertive (Don't waffle), Commit to your story and stay with it... I've given teams very high essay scores, even if they came up with a different suspect than i did because they penned a very organized, logical alternative theory to the crime.
4) Penmanship - If I can't read it, I can't grade it... enough said.
5) Want to lose points in a hurry? make some smart___ comments, or drawings... Did you know that essays can also have negative points? I've even banned kids from any future events that i run!
6) 9 times out of 10, the pen never lies... if you are unsure of who the chemicals point to, go with the chromatography!
7) Don't repeat yourself... I only give you points one time for identifying the suspect and evidence pointing to them... the second time doesn't count and only dilutes the power of your entire essay.
8) Write plainly and try to keep it to one side of a page... Don't ramble, stay concise! Write only what is asked for.
9) READ the instructions... If it says "in paragraph form," I expect to see a few indentations.
10) Not all scenarios have a primary suspect, some have more than one, some have none... Consider all options, but make a solid commitment!

[ShadowMasterZr]

I just wanted to ask: how exactly do you test the plastics? That was one place we didn't do well at one of our invitationals.

[dholdgreve]

I just wanted to ask: how exactly do you test the plastics? That was one place we didn't do well at one of our invitationals.

Don't feel bad... You're not alone! First, let's discuss the theoretical intent... Supposedly, each polymer has a specific density, ranging from around .90 grams / cm3 to as much as 1.49 grams / cm3. The E/C should have at least 5 different liquids, each with different densities. These liquids, list from least dense to most dense are vegetable oil (.885 grams / cm3), 46% alcohol (.915 grams / cm3), fresh water (1.00 grams / cm3), 10% salt (1.10 grams / cm3), and 20% salt (1.16 grams / cm3). by placing a sample of the polymer in the various liquids and determining if it floats or sinks you should be able to determine the the specific density range between two liquids... In other words, if it sinks in 46% alcohol, but floats in water, you know that it must be between .915 and 1.0 density, right? That should really narrow down the possibilities. It's not fool proof... not all polymer samples, even of the same material, have the same density, they vary... also, they can have this very irritating tendency to have air bubbles adhere to them, really screwing the whole thing up, floating when they should be sinking. ALWAYS take your finger and poke them 3 or 4 times to see if you can get them to stay down.

Don't take anything as hard and fast rules... The density test should be used as a guideline only to steer you in the right direction, not as an elimination process.

[caseyotis]

Hello everyone! I just recently got placed in this event for the state competition. A kit with powders and stuff for chemical analysis practice will be arriving soon. For now, how should I practice for this event? What is the most productive thing to do? Thanks!

[computergeek3]

Hello everyone! I just recently got placed in this event for the state competition. A kit with powders and stuff for chemical analysis practice will be arriving soon. For now, how should I practice for this event? What is the most productive thing to do? Thanks!

Learn the powders inside and out. Make observation charts/flow charts to go on your cheat sheet. (Metals can most easily be identified by their appearance).
THEN
Learn the hairs/fibers inside and out. Know what each looks under a microscope.
THEN
Learn plastics. I don't exactly know how to do this for B division...
FINALLY
Learn everything else. At this point, you should have a fairly good grasp on the event and everything should be easy

Hope this helps!

[caseyotis]

Hello everyone! I just recently got placed in this event for the state competition. A kit with powders and stuff for chemical analysis practice will be arriving soon. For now, how should I practice for this event? What is the most productive thing to do? Thanks!

Learn the powders inside and out. Make observation charts/flow charts to go on your cheat sheet. (Metals can most easily be identified by their appearance).
THEN
Learn the hairs/fibers inside and out. Know what each looks under a microscope.
THEN
Learn plastics. I don't exactly know how to do this for B division...
FINALLY
Learn everything else. At this point, you should have a fairly good grasp on the event and everything should be easy

Hope this helps!

Powders. Got it. Like I said, the kits will be arriving soon, with everything in it.
Microscope! Thank you! I was wondering if they had that. I don't have the specs with me, so I don't know...
Okay, I'll figure it out. Is the microscope/hair fibers stuff definitely Div. B?
Everything else. Got it. Thank you! This was helpful.

Hmm... Where should I start? Especially with not having any of these materials yet. Is there anything I can look at to study with?