Egg-less Chicken Embryos and Real Science

Trying a lab for the first time is a great learning experience.  Sometimes we use labs that "work", but it doesn't give us the chance to think through how we could improve an experiment or procedure we've tried to figure out. The students hear from me that real science is trying experiments over and over, making tweaks, and sometimes going back to the drawing board altogether. Trying to hatch egg-less chicks has been a great experience in working on procedure.

Students had a chance to try again when the yolk broke, or the egg was rotten, and because of it, they became more confident in what they were doing. Finally having some success was very exciting. And to see the embryo development that happened in just one day was amazing. I am regretting not going into school on Saturday since when I checked Sunday our best embryo had made so much progress.  I don't know that it will progress much further though, since it looks like the yolk has broken.  I'm still impressed with the development that we were able to see, and now we have more ideas of what to try to make it better.

One of the problems we encountered was too many cups in the oven--next time, no more than 7 since cramming 8 in lifted some of the petri dishes. The embryos with the lifted petri dishes dried out and died. Also, we should only use the eggs with embryos that have made it to the stage of seeing the heart beating.  The younger embryos did not progress well for us. I'm also hypothesizing that it would be better to err on the side of the oven temperature being on the low side instead of on the high side. One last change was to not push down the plastic wrap as low, so the egg is closer to the top of the cup. The theory is that it will leave less air for the moisture of the egg to evaporate into. We're trying to stop dry-out.

Hatching Chickens Outside Their Shells

At the end of the school year last year, one of my students sent me the video of the Japanese students who hatched a chicken in a cup with plastic wrap and no shell.  It looked fascinating and used readily available materials. I decided that we'd give it a try this year when we got into embryonic development.

I did some research and found a couple of helpful resources, one from the Cooperative Extension of the University of Connecticut and one from a text by Cynthia J. Fisher.  We did a slight modification of the procedures to compensate for using an oven. It's really a drying oven that the Chemistry and previous AP Bio teacher figured out where to turn the knob to keep it at 37ish degrees Celsius for the bacteria labs we do.  I pre-heated it on Monday so it was at 38 degrees Tuesday morning.

Note the duct tape holding it shut since we have it a little over-full.

There are several school families who keep chickens. A couple of them have roosters and were more than willing to provide us with fertilized eggs. This past Tuesday, we put the eggs in our "incubator". We added a few more to the incubator on Wednesday--long story, involving an extended school bus ride. =)

After incubating for two and a half days, we cracked the eggs during our Thursday afternoon lab. The yolk of the first egg broke in the process, then the next was rotten. (We had been warned about that potential because of finding some rotten eggs by the "brooding" chickens.) One more broken yolk, and then we had success. I think it helped to have to repeat the process since students got more comfortable with it as we went.  In the end we cracked open a couple of extras and took two videos of hearts beating that we could see. We put them into their "cup homes" for the duration of their development.

To make the homes for the chicks, we used Styrofoam coffee cups, poked a pencil hole in opposite sides of the cup, poured water into the cups up to the pencil holes to provide extra humidity, placed cheap plastic wrap (in hopes the cheap stuff would be more "breathable") over the cup and pushed it down to form a sling, held it in place with a rubber band, and covered it with the bottom of a petri dish.  Eight cups is a tight fit in our little oven, so not all of the petri dishes set well, but so far it appears to work OK.

Today, we checked our chicks-in-a-cup and were amazed by the embryonic development occurring in just under 24 hours!  If I had to guess, students would say it was one of their favorite labs.  And we're hoping it will continue for at least a week, maybe more. The students are voting for all 21 days of course. When we finish, for their lab reports, students will put together a movie of the process. I've included a video of what we've done so far.

Floor Bingo in AP Biology

On Thursdays I have my AP Biology class for a triple period--which gives me two hours with them. This is fantastic for those long labs. We have time to set up, run, and clean up the lab. But this 2 hour class is in the afternoon-the last three periods of the day in fact. I have students come in sometimes with their energy levels so low I feel I need a spatula to scrape them off the desk. I could start each Thursday with a quick Kahoot! which this class is obsessed with, but I wanted something different to get them excited and MOVING if at all possible. As I perused Pinterest, I saw something about BINGO. Our classroom floor tiles are squares, and our room is big enough (if we move the tables) for two 5x5 BINGO squares.

I used Google Slides to make 25 labels--one for each square of the BINGO board.  I kept the labels generic (true, false, A, B, C, D, etc...), so I could use them with whatever topic we're working on. Then I just have to change the questions if I want to use it again when we're in a new unit.  I'll laminate them to help them last longer too.

When I made the questions, I included two copies of each question, and after cutting them all into strips, I paper clipped matching questions together. This way, students will take turns picking a question out of a hat and will have one copy of the question for their team and one copy for the other team.  Each team will lay the question on the square they believe is the answer to the question.  That way, when a team calls, "BINGO!" I can quickly check the questions and answers. It will also allow for discussions about any missed questions.

Here's the file I created for the floor tiles. And this is the set of questions I made for the evolution BINGO game. I also made a set of questions to review for our ecology unit.

We finally did this today in class.  We did it for the last 25 minutes of our two hour class and the students stated active and involved the whole time. =)

Transpiration Lab for AP Biology

Our Transpiration Lab last year was a disaster in my humble opinion.  Our key problem in putting together our potometers was getting an airtight seal of the tubing around the stem of the leaves.  This year we solved the problem of the airtight seal by using a leaf with thicker stems--Pothos.  I had read on the AP Bio forum about teachers using special clips to help keep the seal airtight, but didn't have enough time to find and order them before the lab.  We added a binder clip to the tube where the stem came in.  I'm not sure if the clip actually helped, but the connection there did remain airtight throughout the experiment.

 I did the control conditions and got decent readings, but measured for 42 minutes, which turned out well, since I forgot about the 10 minute wait period to allow it to equilibrate (trying to do the lab from memory). Unfortunately, I have allowed my students to also be sloppy about reading directions since I often will give them verbal instructions to help them get going. Next year, I am planning to make it a practice to give minimal directions and let them read and figure it out more independently.  If I want them to be independent learners, I need to help them in that direction. The lab group testing bright light also had movement of water in their potometer, but not our fan or high humidity group.  None of them waited the 10 minutes before measuring.

I wonder though if our Pothos plant doesn't have a high enough density of stomata to get decent readings from the potometer in 30 minutes (all groups measured about 15.5 stomata per mm^2). I may try a different thick-stemmed plant next year.

I gave them some data afterward so they would still have practice making and reading graphs. 

I know we could move to the whole plant method of measuring transpiration, but we only meet for three block periods a week, Tuesday through Thursday, which makes it a challenge to take readings everyday for a week.

The directions the students use is a version adapted from the College Board's AP Biology Investigation 11 Transpiration lab.  It really isn't an inquiry lab the way we do it, but I like the thinking and math that is required in this lab.

Here's the Transpiration Lab version I use with students (minus the links to our google sheet).