Diffusion Thorugh a Membrane Lab Follow Up

So I already complained about the set-up for this lab. I'm afraid it simply isn't worth the effort. It is on the one hand a cook-book recipe lab, a traditional approach to lab activities that I just don't care for. It is also overly complicated, consisting essentially of three parts, although only two parts are listed officially. But I'm gettting ahead of myself.

Let me list some of the issues.

1. Safety. Goggles, gloves. I guess this is always going to be an issue, what school has a steady supply of gloves for students? I used up all my gloves earlier this year. I tried to minimize any hazard by distributing the chemicals in dropper bottles to avoid spillage. Not enough goggles, so I had to keep reminding people without goggles to keep back from the materials, or switch and put some goggles on - then there's the hygiene issue...

2. Poor instructions. No way were my students going to make sense of the instructions. I had to demonstrate just about every step of the procedure and go over the lab sheets to help them fill it out. At least a cookbook lab should have instructions the kids can follow. I would definitely write a companion set of instruction for next year.

3. Space. Not that there isn't enough, but that the ameneties are inadequate. No sinks, no running water. No outlets for setting up waterbath. Clean-up was as much work as set up, since I could not have every group clean up their own station, since their stations don't include sinks or water. And just going through Part 1 took all of a double period (80 min) with almost no time left to discuss the results. I planned the lab for today when I knew my room would not be used in between my lab periods by other classes, otherwise I wouldn't have been able to clean up. If I were doing this lab again under these circumstances, it would be a demo lab. Sorry. I mean come on, seven test tubes & ten medicine droppers per group? Only one sink and it'a across the hall?

4. Complexity. I would have broken this lab down into at least 3 parts, three days. Part 1: Indicators. Part 2: Diffusion through a membrane, incorporating the indicators. Part 3: Osmosis in plant cells. I realize the idea is to learn about indicators in some sort of context, but this should not be the students' first introduction to indicators - there just isn't enough time to explore them. For example, one of the lab sheet questions asks students to suggest a way to demonstrate that it is the combination of Benedict's Solution and glucose that causes the color change - not just the Benedict's and not just the glucose. But there's no provision for actually testing it (I did as a demo anyway, of course). Likewise, students should have time to explore Lugol's solution with other materials.

Kick myself for waiting until now to do these labs, but maybe doing it this late will get them the extra points they need for the exam. I just hope that with all the graduation-induced haze, they don't go completely brain dead between now & the 22nd.

UPDATE

Final Thoughts on Part 2

About Those Changes

I spoke recently of changes in the air. I am waiting for globat to set up FrontPage extensions on my site so I can publish, and I have finalized, more or less, my plans for next year. I will be transferring to a high school, which will remained unnamed for the moment, until all is settled. I know for certain that I will not return to my current school, and have notified my principal. Separate post on why I am leaving at a future date. My current school has a number of good qualities and lots of good people struggling to do good things, but it just isn't the right fit for me.

So, barring some unforeseen calamity, I know where I will be next year, but I want to get everything completely settled before announcing any details. In the beginning, way back in grad school when I decided to become a teacher, I wanted to teach high school. I never wanted to teach middle school and just basically fell into the job, initially thinking it was a temporary situation to pay the bills. For technical reasons I was never able to make the leap - that technical reason being that I didn't have a secondary science license, which I now have. There were a number of years at my middle school where I thought that middle school was great, and in many ways it should be great - middle school students can be incredibly enthusiastic and fairly easily wowed with science. But getting past the "wow" and into the "how" is often a struggle, and the older I get, it seems, the more difficult it is to deal with some of the nonsense 11-13 year olds can put you through, especially in an large, overcrowded, often overwhelmed school.

I'm excited and a little nervous about the transition. I may well be in for a let down in thinking that high school will be different, but my own experience and what I hear from colleagues is that for the most part the sturm & drang of middle school does indeed diminish in early high school. Either way, the main attraction for me is that I will be able to concentrate on teaching biology, and if the difference between 8th & 9th grade is subtle rather than radical, then I'm certainly prepared to deal with that - 8th graders are actually pretty cool anyway.

Love Teaching, Hate Grading

The thrilling parts of my profession are planning and developing a lesson or unit and implementing it. I actually enjoy curriculum mapping and creating lessons. I enjoy setting up labs in the lab room, even though it takes a lot of time. I like measuring out the materials and dividing them into sets of 10 and preparing the chemicals, the seeds, or whatever - of course I hate the clean up. I love teaching a lesson when students are engaged in class - whether it's a lab, a project, or even a discussion/lecture. I love talking to small groups of students after school about a concept they are having trouble with. I even like preparing PowerPoint presentations, even though it takes me forever to finish one.

I hate grading papers. I know I don't assign enough writing activities to my students, but marking even just 90 student writing assignments (that's how many I teach this year) borders on torture - and if ever there were an argument for smaller class sizes and reduced teaching load in terms of total number of students served, reading student writing and giving meaningful feedback to help them improve their writing skills is it.

Based on the work I receive (written reports on exit projects, e.g.), the process of writing must be as painful to the students as the correcting process is for me. Even without the basic grammar & spelling problems, their thoughts are a tangled mess of knotted and twisted logic. The ideas are out of sequence, the point of many sentences is unclear, the idea may be clear but isn't really relevant to the topic, the major topic they are supposed to address is nowhere to be found - And I have to try to give comments that convey these deficiencies. I try to give positive comments as well, obviously, but sometimes that's nearly impossible except to note that they did a good job of starting sentences with capital letters and ending them with a period. I suppose that's worth something, but we are talking here about an accelerated grade 8 regents class!

So as I sit here this Memorial Day weekend going cross-eyed, I dreamed up an idea for a program to provide one-on-one tutoring for students who need help with writing. The idea came to me as I was editing a couple of papers that were submitted to me via e-mail by a couple of students. I decided to try editing in MSword - which I had never done before - and sending the edited papers back to the students via e-mail. It was surprisingly easy, and for someone like me with remarkably poor penmanship, the added bonus is that the students will actually be able to read my comments. And I thought, what if I could get some local college students to volunteer (or write a grant & pay them) to do this with students? A minimal amount of training would be necessary, and the volunteers would help students through several drafts of one major writing assignment. Almost all of the contact would be through e-mail, except perhaps for an initial meeting and an end of the year expo or something to celebrate their work.

Now, I know that there are models out there for students to help each other through peer editing and whatnot, but I frankly don't want to spend science class time having students edit each other's writing on a formal assignment such as an exit project. And I wonder how effective that strategy can be in a science class, where everyone may be struggling with the content understanding. Would the students even be able to formulate questions to guide their peers to express an idea more clearly? Would they be able to recognize when a process is completely out of sequence, or that a sentence is totally off-topic? I'm pessimistic on these questions, but then again I haven't really tried the strategy.

I still think back to my own experience with writing, which you may have noticed doesn't come naturally. I was in grad school faced with writing an 80-page master's thesis. I had always found writing even 5-page papers a struggle, and here was this monumental task in front of me. I couldn't have done it without the help of my wife, who was my full time editor, proofreader, & critic throughout the entire process, draft after draft. That's how I learned to write. It is still a struggle, but at least I know what I need to do. Whether I actually take the time to do it is another story.

Writing a full-fledged lab report must be a similarly daunting assignment for our students, and yet they get little support for the writing process. I think I'll look into this idea a little more.

Update

Somewhat on-topic, a NY Times piece today criticizes the new essay portion of the SAT. Relevant because it shows the new importance of writing skills for students today, the article criticizes the approach, which apparently values Bill O'Reilly style certainty over studied analysis & consideration of opposing viewpoints.

Lies, Damned Lies, & Rhetoric

(See Update Below)

I try to avoid blogging about political issues, but this one has my blood boiling for a couple of reasons. The New York Times reports that the Smithsonian Institution's National Museum of Natural History is screening a film by the Discovery Institute that tries to make a case against evolution. First of all, the Discovery Institute is one of those slimy "think tanks" whose mission is to promote right wing conservative ideology. They employ a hardball rhetorical approach that is, in my eyes, a worse offense than outright lies. The announcement of the screening of the movie at the Smithsonian is a typical example of this method:

The president of the Discovery Institute, Bruce Chapman, said his organization approached the museum through its public relations company and the museum staff asked to see the film. "They said that they liked it very much - and not only would they have the event at the museum, but they said they would co-sponsor it," he recalled. "That was their suggestion. Of course we're delighted."

The truth is that the Smithsonian officially "co-sponsors" any film that is screened at the museum. The rhetoric implies that their film received special treatment because it was so intriguing. And I thought honesty & integrity were "conservative" values. How naive of me.

Now, the obvious point that should have everyone concerned is that the National Museum of Natural History is screening a film at all that tries to discredit evolution. The anti-evolution camp has done a great PR job in convincing a lot of people that having their voices heard is all about fairness and balance. This of course appeals to everyone's democratic sensibilities. The New York Times article even falls prey to this fallacy, reporting blandly:

Although Charles Darwin's theory is widely viewed as having been proved by fossil records and modern biological phenomena, it is challenged by those who say that it is flawed and that alternatives need to be taught.

To show how silly this statement is, substitute the idea of a heliocentric model of the solar system for "Charles Darwin's Theory:"

Although the heliocentric model of the solar system is widely viewed as having been proved by astronomical observations, it is challenged by those who say that it is flawed and that alternatives need to be taught.

See how stupid that sounds? Would you want your tax dollars supporting the screening of a film that supported the discredited notion that the earth is the center of the universe? The Times refuses to state the fact that "those who say that it is flawed" are almost universally political and religious hacks and NOT biologists. That seems to put the showing of the film squarely at odds with the museum's policy not to sponsor "events of a religious or partisan political nature."

The fact is that there is no scientific debate about the validity of evolution. It is purely political and the Smithsonian should be ashamed.

UPDATE

For more commentary, see the following blogs, which place a lot of emphasis on a point I left out, which is that the deal is essentially payola - the Discovery institute is paying the Smithsonian $16,000 to show the film to a private (and trust me, sympathetic) audience. I also implied above that tax dollars are being spent showing the film, when in fact the museum seeks to make money from the deal:

Panda's Thumb: Smithsonian Warming to ID?

Pharyngula: The Discovery Institute at the Smithsonian?

UPDATE(6/3/05)

Washington Post: Smithsonian Distances Itself from Controversial Film

Panda's Thumb: Fumble in the Endzone

The Smithsonian has withdrawn their status as "co-sponsor" of the Discovery Institute film, "Privileged Planet." Apparently outraged at the way the Discovery Institute was implying that the Smithsonian endorsed the film, they also are returning the $16,000 initially paid by DI to show the film. They will still show the film as per the original contract.

Diffusion Through a Membrane Lab Set-up

I spent several hours today setting up the fairly elaborate lab required by NY State for the regents exam, "Diffusion Through a Membrane." It's a nice enough lab, but way too much set-up for teachers in my situation, in rooms with no running water that are used by multiple teachers and classes throughout the day. The basic idea is to produce cell models with dialysis tubing, cut into segments, filled with a mixture of a starch solution and a glucose solution, and tied at both ends a little like a sausage link. This "cell" is placed in a hypotonic environment (distilled water) into which a few drops of Lugol's iodine solution is placed.

While allowing the cells to soak in water, students will perform a series of tests, using known solutions of starch and glucose, plus Benedict's solution and the iodine mentioned above as indicators. They will observe that the light blue Benedict's solution will turn orange/red when heated (water bath method) if glucose is present, and the Lugol's solution will turn black in the presence of starch, without heating. There are of course controls to show that it is indeed the glucose & starch that are responsible for the color changes.

Meanwhile, the little cell will have turned a dark purplish-black color inside, showing that iodine has diffused across the membrane into the cell. A test of the distilled water outside the cell will reveal that glucose has diffused through the membrane out of the cell. The color of the distilled water outside the membrane will remain amber from the iodine, indicating that starch has not diffused out of the cell through the membrane.

• Glucose - diffuses out of the cell, no indicator in the water, so no color change. Only detected when water is added to indicator and heated.


• Iodine - diffuses into the cell, turns color inside the cell to indicate starch.


• Starch - does not diffuse out of cell, so water outside cell with Lugol's does not change color. Inside cell turns blackish.

And that's just Part 1! In part 2 We get to hook up the microscopes and watch onion cells shrivel or plump up when placed in saltwater or distilled water environment.

Follow-up Post

Syndication Part 2 - The Ordeal

I finally figured out the proper settings to get my site feed going to the right place. I thought I had this figured out earlier, but it turned out that blogger was publishing my site feed to one directory and bloglines was reading from another directory. I had to do a number of "experiments," altering one variable at a time (the FTP Feed Server Path) until I got my everything in order. I also had to ultimately RTFM from my web host (Hostway) to determine the proper path. This is only a problem for people like me who are hosting a blog on their own websites. If you let Blogger host your blog, it's pretty much automatic.

Updated Lab List

A lot of discussion on one of my listservs about lab minutes. The regents curriculum requires 1200 minutes of lab before students are allowed to sit for the exam, but what exactly constitutes 1200 minutes is not entirely clear. It seem to be pretty much up to the teacher to determine what labs to do (aside from the 4 required labs) and how many minutes to assign to the lab.

I personally assign a certain number of minutes to each lab, based on what I think is a reasonable amount of time for my students. I fully expect to go pretty far beyond the minimum requirement anyway, so I try not to get too caught up in it. This excess also reduces the need for make-ups, which I find logistically impossible anyway - if a student is absent for a lab, they just miss the lab.

So here is a list again of labs I have done or expect to do before the exam. I will work on linking to any worksheets I have in the next few days. Most of these are "homemade" labs and don't require sophisticated materials/equipment:

#__________Name_________________Minutes

1. Peanuts Observation.....................60

2. Mental Models/Black Box...........120

3. Mendel’s Pea Plant Simulation....45

4. Alien Genetics..............................90

5. Mitosis/Pipe-cleaners..................90

6. Egg Osmosis...................................90

7. Finches’ Beaks (NY State)...........90

8. Microscope review/skills.............60

9. Pasta DNA models........................120

10. Digestive system models...........90

11. Hot Salsa Lab...............................90

12. Mello Jello Lab.............................90

13. Sheep Heart Dissection..............90

14. Vital Signs (GK-12).....................90

15. Exit Projects.................................120

16. Making Connections (NYState)...90

17. Diffusion/Osmosis (NY State)...180

18. Biodiversity (NY State)..............180

19. Frog Dissection............................120

20. Flower Dissection/Seed/Plants..90

21. Respiration/Photosynthesis........90

Total Minutes........................2085

UPDATE

The last three are, sadly, off the list. Prom and graduation rehearsal killed them. That's one of the disadvantages of teaching regents in middle school grade 8. That makes about 1785 minutes.

Syndication

I keep up with the blogs that I frequent by "subscribing" (despite the term it doesn't cost anything) through bloglines. You can click on the icon below to subscribe to this site with bloglines, set-up is pretty painless:

Basically I can click on my bloglines bookmark and see on a single webpage if anything new has been posted to the blogs that I read. This spares me from clicking through all the blogs in my list when most are not updated daily. The only downside is that comments aren't included, so I still wind up clicking through to see if any new comments have been posted on certain blogs. Still, as my list of blogs increases, the need for a service like bloglines increases.

I was having difficulty getting my own blog to "syndicate." All this terminology is a bit confusing - syndicate, subscribe, site feed - they all refer pretty much to the same thing, only the reader "subscribes" to a website's "syndication" or "site feed" - enough already. I certainly won't go into the different protocols available for this purpose. At any rate, I finally got the settings correct so that I or anyone else can now subscribe to my blog. I'm posting this message in part to test that I've got everything set up correctly. As infrequently as I post, it's a worthwhile effort if you find yourself clicking on my link frequently and finding nothing new. I know that can eventually become a disincentive to visit.

I have also been searching today, unsuccessfully, for other biology teachers who might be out there, anywhere, blogging about teaching biology. If you stumble upon this post and know of any, let me know through the comments button below.

Update

I neglected to mention that you can also use bloglines to subscribe to news organizations, even specific news sections that you want to subscribe to. For example, I've subscribed to the New York Times Science Section, the BBC Science & Nature feed, and Scientific American. You can get similar services by using e-mail updates, but I find I just delete most of the e-mails I get from these sources before I even have a chance to read them. It's just more convenient for me to have it all on a website that I can click on and get the latest information that I'm interested in.

Practice Exam Part 2

I marked the multiple choice section of the second practice exam, just to gauge where the students are and identify students who will need some extra sessions for the next 4 weeks in order to have any chance of passing the exam with a 65 or better. Let's just say the panic I mentioned in the previous post is pretty well justified. I walked around during the exam and noted that students were struggling with the written response questions, so I decided not to mark those sections directly - I don't want to dash their hopes! Instead, I will have students work with each other in discussing and revising those sections next week. We will then go over together using Annie Chien's Regents Review Community.

I can't get over the fact that in one class I could have a student score 32 out of 35 multiple choice questions correct and another student score 8 out of 35 questions. The average was around 20. Keep in mind that using scaled scoring, for the whole exam a raw score of 39 out of 85 is passing with a 65 - that's only 46%. Using that same percentage, 16 out of 35 on the multiple choice section would be a passing score. Of course I realize that the multiple choice questions may be a little easier, especially for my writing-challenged students, but still I have some hope that a high percentage will pass the thing.

I've scheduled three days per week after school, for about 30-40 students (out of 90!) who need help, some more than others. My colleague who teaches one section will take one day, I will take the other two. I don't expect all students to show up for all three days, and there will probably be some overlap in the review topics. We will break them into smaller groups of 10-12 students.

I thought January 2005 was a particularly difficult version of the exam, certainly harder than the practice exam we did for midterms (June 2004 exam). Are the January exams intentionally more difficult?

Change in the Air

A number of changes to talk about in the coming weeks, and a time to look at the state of things as this school year approaches an end.

First the changes. It looks like I will not be teaching Regents Living Environment at my current school next year. That can be interpreted in a couple of different ways, and I will leave it ambiguous for the moment. That also leaves open the question of whether this blog becomes obsolete next year - or at least the title.

The second change is that I am looking for an alternative hosting set-up for my website. I currently use Hostway, which has been excellent - I can't remember a single moment of down time - but I can't afford it any more, and I'm looking for a number of ways to cut back on expenses. I started with hostway back when I was setting up the website as a staff developer for District Six in NYC, and the district picked up the tab. I'm looking for reliable cheap alternative hosting, but I may have to settle for cheap. I'm looking at Globat, which has some special offers from gotapex. All this means that there may be some down time as I make the switch.

End of year issues. I'm in full regents prep mode as panic sets in. Of course students are getting less & less focused on school because that's just what happens in middle school - Most students have no more real exams left. The 8th grade science & social studies tests are jokes in the sense that there are no consequences for students or schools if the students don't perform well, so there's little pressure on anyone to take them seriously. So here I am asking them for the first time in their lives to be serious all the way to June 22nd when the Regents exam is scheduled. They know that they will be in school with me reviewing for an exam even when most of their classmates are finished ("graduation" is June 16th).

My colleague (who teaches one regents class) and I will begin extra tutoring sessions next week for students in danger of failing the exam. I'm giving my final practice exam this week to gauge who needs the most help. I'm hoping that only 15-20 kids (out of 60) will require extra help. As I've stated before, because we are an 8th grade program, I want everyone to get 75 or better on the exam so there won't be any hassles with their high schools because they barely passed. I know that all students at 75 or better is probably unrealistic at this point, but it's still a goal.

Still left to cover. Student exit projects are due next Friday. I've been helping them along with the different parts of the written report, and will post a few when they are done. I will also post some of my strategies for getting the written part completed. In short, they will hand in different elements of the report each day between now & next Friday (I don't have any revolutionary fool-proof methods here). This will allow me to give them feedback pretty quickly for editing. By Friday they will have to fix any problems and put it all together.

I still have some ecology concepts to cover. Most of the basics were taught last year, so I don't have to do a full ecology unit. Just review and elaborate. I will need to do a lab on plants along with photosynthesis/respiration.

I need to review evolution and particulary human evolution. That will have to be a quick powerpoint presentation, unfortunately. Ditto for biotechnology.

Finally, I need to do 3 more required labs. It sounds like a lot, but I do get 8 periods per week (minus some days for end-of-year nonsense). Also, most of the basic ideas in the required labs have already been covered to an extent in other labs. If I teach LE again next year, I will know much more about time management than I did this year. I spent too much time on some topics (relative to their importance in the exam) and too little on others.

Student Blogs Revisited - Again

I haven't quite given up on student blogs, but I am going back to a modified version of my original plan, which was to have a single blog for an entire class, with students now contributing the posts instead of me posting assignments and asking students to respond in the comments section.

I probably should have anticipated the difficulty in monitoring several student blogs at one time, but I was overly ambitious and optimistic, as usual. What's that line about people repeatedly doing the same thing over and over and expecting different results? (Definition of insanity).

I am a little surprised that students didn't take some initiative on their own - after all, I made it acceptable to write about things other than science on their blogs, but all I got was a few students doing a couple of posts for extra credit, then basically abandoning their blogs.

So I will link again to the original Class Blogs - 801 & 807 - and Monday will give students assignments to post their ideas for extra credit.

Exit Project Questions

I promised (long ago) to post some of the projects that my students are working on. I repeat that I needed projects with relatively short data collection times, since my top priority is preparing for the Regents Exam. I was not concerned with students coming up with elaborate or novel ideas, and am more concerned that they do a thorough job with a simple idea and be able to explain their results at a pretty sophisticated level. I gave them a deadline of May 6th to finish with data collection, anticipating another week or so to process the data, write up their results, and present their findings. I have donated class time - a double lab period once per week - and have made myself available to them after school if they need extra time or help. So, here are a few more projects that my students are doing, written as problem questions, with descriptions following the questions.

How does temperature/pH/detergent concentration affect enzyme action?


A follow up on the lab we did called mello jello. Enzyme action is measured by the increased diameter of a well cut out of a jello sample, filled with detergent solution. The original lab looked at various detergents, students' projects manipulated one of the other variables listed in the title - in other words, three different experiments/projects came out of this lab.

How do different foods affect mealworm growth?


Student has three containers with 20 mealworms each, records mealworm growth(measured in grams) after several weeks. Student also keeps track of molting to the extent possible and metamorphosis where applicable. Student will be expected to explain results based on some measurable quality of the foods involved - caloric content, texture, moisture content, etc.

How does weight affect heart rate?



Students are taking measurements of subjects at rest, walking, and running short distances and correlating with weight/height, body-mass index.

How does height affect speed?



Students are testing subjects of various heights and looking for correlations with time it takes to run a certain distance.

--A lot of seed germination projects - temperature, salt content, light exposure, size of seed.

How do different concentrations of detergent affect DNA extraction from wheat germ?



A variation on the lab we did on DNA extraction. Using protocol, altering only one variable in the procedure. Student will extract DNA, dry on filter paper, weigh the results.

NOTE: I purchased some inexpensive twin beam balances that measure to 0.01 gram precision.

How does the mass of a lemon affect the voltage produced by a "lemon battery?"



OK, so they are actually using oranges for some reason. Pretty self-explanatory. My only comment is that they somehow have to look at this more from a biological perspective rather than physical science, but of course the distinction is rather artificial in the end. What I means is, what does the lemon battery have to do with the functioning of living things?

That's enough for now. For anyone reading these titles after searching for science fair projects, I would only point out that each of these projects, as I constantly stress, has a measurable dependent variable and each is looking for a cause and effect relationship, or at least a correlation between two variables. The New York City Exit project requirement states that all projects should follow this model, whether it is a controlled experiment, a field study, or a secondary research project. Even design projects should include a controlled experiment to test some aspect of the design. You can check out the old District Six Project Guidelines for a more complete discussion of these different projects.