Before actually beginning the unit I would like to take a moment to talk about the science journal. It is an excellent way to tie writing into the unit and also makes students sharpen their powers of observation. The structure of the journal that is proposed requires the students to keep track of class demonstrations and experiments using the scientific method as an organizing tool. A few years ago I was introduced to this learning tool when I was part of a language and vocabulary project that the bilingual classes in our school were piloting. Even though our students were English speaking many of the teachers in our school saw the project as one that would benefit our students. Within each science journal entry there is an opportunity for the students to broaden their vocabulary and use new terminology while doing activities they enjoy. The journal not only familiarizes the students with the scientific method but also helps to build a foundation for participation in the citywide science fair. Making this a permanent part of the science curriculum will reap benefits beyond the scope of this unit. Every child is to have a science journal and if they aren’t familiar with the scientific method they should be introduced to that as they do the first experiments. All demonstrations and experiments should be entered in their journal during the unit. See Lesson Plan #1 in Appendix for more details.
In beginning the unit, there are two main teaching objectives. First, to get the children interested in the topic, and second, to begin with a familiar or relevant experience from their own lives, which they can relate to. In this unit, the process of human respiration is the starting place. Again, I would begin with a question: What do all humans and animals need to live? Children will readily mention food and water, and inevitably mention air. At this point the children would be asked to do a simple demonstration.
Breathing is an involuntary activity that we do automatically. What would happen if we try to consciously alter the rate at which we breathe? If we ask the children to breathe very rapidly and deeply they should very quickly feel a bit dizzy and their breathing will slow down. What happens is that we are building up the amount of oxygen in our blood while the amount of carbon dioxide was falling. Soon our brain sends out signals that we have enough oxygen and our breathing automatically slows. If they then do the opposite and try to refrain from breathing no matter how long they are successful they will soon be forced to breathe because the air in their lungs must be released and fresh air brought in.
The first experiment is going to have each child do three main breathing activities: How fast do they breathe when they are inactive? How fast do they breathe after exercising? And, how long can they hold their breathe? (See Appendix A, Experiment #1) 1
Coming from this first activity the children should understand that breathing is important to all human beings and animals. It is so much a part of us that we cannot control it and it is something we must do.
Since we know that we need to breathe just what happens when we breathe? What is the process? The teaching objective here is to have the children understand the breathing process in humans so we can compare it to the process in plants.