New Unit - Animal Kingdom

Today, we introduced a new unit of study in class, the Animal Kingdom. At each lab station I placed samples of preserved animals, models, or skeletons of the various phylum (annelids, mammals, fish, amphebians, cnairdians, porifora, birds, arthropods and reptiles for example). The students went from station to station trying to name the group of animals, and to determine if the group were invertebrate or vertebrate animals. This was a sort of a K-W-L activity to see what the students knew about animals. We did not define what an invertebrate or a vertebrate was as this is a seventh grade class, and we really wanted to see what knowledge base they possess. The kids were definetely involved in this activity and exhibited high levels of interest. We currently have a pair of ringneck doves and several rats in the classroom which the students love to observe, care for, and interact with.

Baking Bread - A real world application

It is important for our students to understand why we study the curriculum that we do, and where will it apply in their everyday lives, therefore, as a follow up to our lesson and lab on yeast respiration, we made bread. I pointed out that for centuries we humans have been taking advantage of the process of yeast respiration for our own benefit. Yeast are used in baking, cheese and yogurt production, and in fermenting wine and beer. The emphasis in talking about the process of bread baking was on the requirements for yeast growth (food source, warmth, darkness, and moisture) and how the recipe fullfills these. I also stressed that the bread rises because of the carbon dioxide which is being released as the yeast cells respire. In a previous lab, the students had studied what yeast need to live by "proofing" yeast. They had set up a beaker with yeast and water (the control), and a second beaker with yeast, water and sugar (the experimental sample). They then made a wet mount slide of each sample, staining the yeast in order to see them and count them. The samples were then left overnight in a warm, dark place. The following day the students again prepared wet mount slides of each sample and discovered that sugar caused an increase in the number of yeast cells.

Studying Respiration in Yeast

In order to study respiration in yeast we set up an experiment using Bromothymol Blue (an indicator which is sensitive to the pH changes that result when carbon dioxide is dissolved in it), sugar, live yeast cells, and dead yeast cells (yeast were boiled). The students set up three test tubes with 15mL Bromothymol Blue solution and 2 grams of sugar. The first test tube served as a control containing only the Bromothymol Blue solution and sugar. The second tube had live yeast cells added to it, and the third had dead yeast cells added. The samples were then placed in a warm, dark room to incubate over night.















This lab group had an excellent result. From left to right the dead yeast tube, the live yeast tube and the control tube. Some lab groups had tubes that exhibited contamination in the dead yeast tube. Several groups had forgotten to clean their test tubes prior to beginning the lab. Lesson learned, never assume that your glassware is clean even if it looks clean. Of course we are not working under sterile conditions and some contamination is to be expected.

Edible Fungi Models

We made edible fungi models in class last Friday. The cardboard base represents a food source (tree branch, fruit, or piece of bread), the red and black licorice represent the hyphae, the tootsie pops standing are asexual spore cases, and the lollipop tops (orange in this model) represent sexual spore cases where +parent and -parent have met. The students had a blast making the models, and eating the extra modeling materials. If you can't get hold of shoe string licorice you may use two different colored yarns or ribbons.

Lichens

Lichens are a symbiotic relationship between fungi and either algae or photosynthetic bacteria (cyanobacteria). Yesterday and today we have been observing lichens in the classroom. For some students it has been hard for them to understand the concept that lichens are composed of two different organisms. One source of difficulty has been in preparing wet mount slides of crushed lichens. It is very easy to observe the algae, but harder to see the fungi hyphae. Any suggestions would be helpful.

International Space Station Viewing Opportunities

At school this morning the principal announced that in our area the International Space Station was scheduled to pass directly overhead and the sighting was expected to last up to 5 minutes. You can visit NASA to get information for sightings in your area. The station is best viewed at dawn or dusk when the sun is reflected off it. We took the opportunity to refresh the kids knowledge of how to use a compass in order to locate the station in the sky. Luckily, we had a compass for each student to use. Several students signed up to borrow a compass to use at home tonight. This was also a time to discuss NASA's future plans for space exploration and the role that the space station plays in endeavor.

Bread Mold Lab

In the grade 7 Life Science classroom I am currently doing my student teaching internship in, the students are studying mold and fungus. Prior to leaving for Winter Vacation, the students innoculated homemade bread with spores from a moldy orange, sealed the bread in ziplock bags, and placed the bags in their lab drawers. Today, they took out their samples to view the results. First, the students observed the mold using the dissecting microscope. Second, they prepared wet mount slides to better view the hyphae and spores using the compound microscope. We had some great results. One student decided to try lifting the mold off the bread using scotch tape. She had an excellent result! Good thinking!