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Equipment and Supply Modifications
Alternative Lab Ideas
Comment: " . . . My daughter takes after me -- at 15 she weighs 87 pounds and is 5' 4.5" tall. She experienced some fainting spells from the time she was about 12 and the pediatrician thought it would be a good idea to have a cardiologist look at her. She is NOT anorexic, but very active and runs cross country. Anyway, the cardiologist ran a number of tests and found that her heart is just fine. What she has he called POTS -- for postural orthostatic tachycardia syndrome -- meaning that when she stands for long periods without moving (church choir), or gets up too fast, she will pass out, and her blood pressure goes very low. The cardiologist even induced her to pass out while strapped to a cot and hooked up to monitors. He attributes this phenomenon to low blood volume (she doesn't have a whole lot of tissue to fill with blood, being so tiny). He happens to be doing studies on anorexia and blood pressure, and assures me that she is just fine. He told her that she must drink a lot of water, so she carries a water bottle around school, and that I shouldn't hold back salt from her, to encourage water retention. He also told her to 'fidget' whenever she has to stand for long periods, to help the blood return to the heart. She hasn't fainted since!"
-- Cindy Botsford, Westwood Junior/Senior High School, Westwood, New Jersey. 3/6/00
Equipment and Supply Modifications
Tip: "Regardless of what the directions say, I always have the best luck keeping Daphnia in the refrigerator, rather than at room temperature. I throw in some yeast for food if I want them to last more than a few days. Sometimes it looks as though the whole culture is about gone, then one of the dying old females releases tons of babies into the water. Presto! Good luck!"
-- Barbara Beitch, Hamden Hall Country Day School, Hamden, Connecticut. 3/25/99
Question: "Does anyone have a suggestion for something other than the Daphnia to be used in the circulation lab? I always have tremendous amounts of trouble isolating the little guys and keeping them at the different temps. Is there something bigger or easier to see?"
Answer 1: "We raise medaka fish in the classroom for developmental studies in Anatomy and in AP Biology. Using the eggs for heart rate and temperature is a bonus and the eggs will still hatch after the lab if care is taken. Medaka eggs hatch in about 14 days. The heart is beating very early on in development and it is easy to count the beats. Zebrafish work well, too. Both fish are easy to photocycle to get them to lay eggs. Zebrafish hearts begin beating within 24 hours of the eggs being laid. The Web site, WWLPT Biology Institute: Life Cycles -- Reproduction & Embryological Development, provides information about using fish eggs instead of Daphnia." (See below for link)
-- Nancy Hein, Hawley High School, Hawley, Texas. 3/1/00
Answer 2: "Wards sells some neat little clear plastic gadgets that let you 'imprison' a Daphnia in a water-tight container. It is then easy to float this in a finger bowl of water at a certain temperature. Since I started using these, I've actually gotten relatively good data."
-- Anne Soos, Stuart Country Day School, Princeton, New Jersey. 3/1/00
Answer 3: "While the Daphnia lab is a tough one because we're working with live critters, it's a great opportunity for our students for just that reason. Why do we think that everything should be neat? Science is a messy business and kids need to realize that. I think it's what you can do with the data afterwards that really counts. I have my students write short stories or narrative poems based on the lab data and everything is from the Daphnia's point of view. I've gotten some awesome stuff over the years, including take-offs on How the Grinch Stole Christmas and The Adventures of Daphnia Jones. Students need to include a conclusion in this assignment in which they can discuss their results and why they think things happened the way they did."
-- Cheryl Hollinger, Central York High School, York, Pennsylvania. 3/2/00
Answer 4: "Another choice for circulation might be Lumbriculus. These worms are easy to culture and care for. There are a number of Web sites that have information. Woodrow Wilson has a site that has lots of similar labs and the best one is by Charlie Drews in Iowa. Just type Lumbriculus on your search engine for lots of hits."
-- Mike McNabb, Ballard High School, Louisville, Kentucky. 3/1/00
Procedure Modifications
Question: "The blood pressures of the little tiny skinny girls in the class are invariably very low; off the charts given in the lab. I have never been sure if this is a 'true' observation, or if for some reason it is just harder to hear accurately when reading the pressure of the little tiny skinny girls. Anyone else noticed this?"
Answer 1: "You have to make certain you use the correct size blood-pressure cuff for the size of the arm -- some of these tiny people should have their blood pressure taken with a pedi cuff, and some of your super-big football player types should have theirs taken with an extra-large cuff. I learned this in Physician Assistant training."
-- Marcia Sloan, Cleburne High School, Cleburne, Texas. 3/5/00
Answer 2: "It might be that youthfulness itself contributes to the lower blood pressures. Their vessels surely must still be elastic and flexible. For years I have had girls with blood pressures around 100/60 in my classes -- I always told them to enjoy the luxury of their young healthy bodies!! I have never associated the lower blood pressures with thinness in my classes. We don't have boys to compare with so I've just naively assumed that blood pressure averages for teens would not be 120/70. I think that is a figure listed for adults, isn't it? It would be great if the lab manual writers for high schools would give comparative data for teens whenever it is available." ."
-- Charlotte Freeman, Girls Preparatory School, Chattanooga, Tennessee. 3/6/00
Answer 3: "I think that the reaction -- and possibly some other data from this lab -- is classic 'vaso-vagal' response. Many people experience this around anything 'medical' -- dentist chair, blood drawing, etc., etc. I have seen it in students during the finger-poke needed for blood typing, and during movies where surgery was graphically displayed."
-- Mike Nolan, Rainforest and Reef 501, Grand Rapids, Michigan. 3/6/00
Alternative Lab Ideas
"By the way, if you have the Vernier EKG probe and the biology manual they publish, the EKG lab has a neat way to analyze segments of the graph. You can scroll across the screen and measure the time for the P-R wave, QRS, and QT. They give standards for comparison and it enables us to talk about how EKGs can be useful to detect fibrillation or blocks in the conducting tissues. I'm trying it this week for the first time. This BP discussion does make me wonder what I will do if someone is way out of the normal range. I remember 30 years ago when I was teaching college A&P that I detected a very strange pulse in a student -- so bizarre that I told her to ask her doctor the next time she went to explain it so I would know. Turns out that she had such a severe valve problem that her heart was already the 'size of a cantaloupe' and she was a competitive swimmer. At that time she was considered to be in severe trouble and I remember a thank you note from a parent appreciating the fact that I did not ignore that strange symptom. Once I had a 'skinny' high school student with a BP of 200/135 and I rechecked it about four times. She too sought medical help and was put on blood pressure medication. HOWEVER, these two instances notwithstanding, I wonder where our responsibility begins and ends."
-- Charlotte Freeman, Girls Preparatory School, Chattanooga, Tennessee. 3/6/00
Tip: "Alternative Creature: Many of you have inquired after alternatives to the use of Daphnia for AP Lab # 10. There is a company called Cricket Science (1611 Shane Drive, Pocatello, ID 83204; Fax: 208-232-5548). They offer videos and an audio cassette dealing with crickets. The audio cassette is of interest to us: Myths & Science of Cricket Chirps (Item # 20 / $15.95, with teachers' instruction guide). The tape includes cricket chirps recorded at a series of different ambient temperatures. The crickets' chirp rate correlates with the metabolic rate, which changes with the temperature. Therefore the students count and record cricket chirps at different temperatures, then graph the data and calculate a Q10. Works nicely."
-- Judy Bicknell, LaGuardia High School, New York City, New York. 4/7/00
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