It’s all connected!
T M Srikanth
“Acceleration is the rate of change of velocity.” This was the definition of acceleration that I had just taught students of class 8. The response was blank looks. So I thought I would make it easier by using word associations. I asked the class what they understood by the word “rate”. Pat came the answers: ‘cost’, ‘money’, ‘price’… No matter how hard I pushed, I never got the answer for this context: time.
In another instance, we were learning about “displacement”. Again, all I got were blank looks. Displacement is defined as the distance travelled in a specified direction. But in normal conversation we always use words like ‘far’ and ‘near’ to indicate distance. If asked where you live in the city, you would not say ‘northwest’ or ‘southeast’. Instead you would use specific landmarks. So, to say that displacement is distance travelled in a specific direction leads to confusion.
There are plenty of such examples. Children are taught that light travels in a straight line. Then they are told that light bends and the word ‘refraction’ is introduced. Newton’s Second Law of Motion states that “the rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force”. Simply put, this means that if you apply force on a stationary or moving object, it will change its direction. We face a similar problem with mass and weight. While science itself is very precise, its language is anything but precise.
With so much confusion in a child’s mind, it becomes the responsibility of the teachers to clear all this confusion. Making them learn the definitions via the rote method leads to fear and many children are afraid of science because they do not see themselves using these concepts beyond school. Today, all these definitions and concepts are available at the click of a mouse. Understanding the logic behind these is more important than just memorizing them. Teachers should ensure that science is taught without jargon and unnecessary rhetoric.
One way of making science learning more meaningful and interesting is to allow the child to explore the intricate connection between the three main branches of science in school. I firmly believe that the differentiation into physics, chemistry and biology was more for human convenience and that these are interlinked because the knowledge source is a single one.
As the Academic Director of Vidya Vanam School in Anaikatti Coimbatore, I have been involved in the recruitment of science teachers and have found that a chemistry teacher is willing to teach biology but not physics. A physics teacher would rather teach math than biology or chemistry. This stems from the lack of understanding of the intricate connection and interplay of the various scientific subjects in our daily lives.
If teachers are asked to teach the students about the connection between these three subjects from junior school, say class 3 onwards, we may be able to overcome this diffidence. This is not to say that the syllabus, whatever it might be, should be ignored. What we need is more innovative thinking by the science teachers. Most schools have a single science teacher for the junior classes and individual subject teachers in the senior ones. Therefore, it becomes necessary for the subject teachers to establish the connection between the science subjects even as they teach individual topics. It also becomes necessary to establish in the child’s mind the connection between the three subjects. If a child has to develop a liking for a subject, it is essential for him/her to see how the subject(s) has an effect on daily life. If we can make that connection, it will go a long way in dispelling the fear of science in our children.
Take the topic of force and motion for example. In physics, we invariably look at the motion of a car or a train or form of transport. Why not look at the motion of molecules during a chemical reaction or within the human body. The circulatory system and the muscular system are both ideal examples of motion in the body. The human heart is similar to the carburettor of older cars. When the car is started, electricity is generated in the spark plug, which then moves the fuel around to power the car. This is similar to how oxygenated blood is circulated and transported throughout the body.
Another example is teaching the concept of fulcrum, load and effort. The general practice is to show them a see saw, a nut cracker or a scissors and explain the concept of fulcrum in the middle; the load at one end and the effort at the other end. If the same concept can be taught using the elbow joint, the knee joint and the shoulder joint, not only do the concepts become more interesting but the child will also think along these lines when picking up or kicking a ball.
Similarly every reaction in the human body is a chemical reaction because the minerals that we eat are chemicals; the only difference is that they are naturally obtained from our food. Breaking down of food is a chemical reaction and hence a chemistry topic is also a biology topic. The heat released during this process also can be introduced in physics as convection and/or conduction. The process of breaking down food is by molecular motion, which again moves between the three subjects of physics, chemistry and biology. When we develop a fever, there is a biological reaction of release of antibodies to fight the infection. These antibodies are chemicals that are naturally found in our body. But, to find out the extent of fever, we have we use a thermometer. Here again the interplay between the three subjects is evident.
Another classic example of the connection between physics and biology is the nervous system. The nervous system is like intricate electrical circuits. When current passes through a circuit, there is a certain output depending on the resistance connected to it. Current is the movement of electrons through a wire. The wires in the human body are the nerves and there is a constant flow of electrons in the nervous system. Any resistance to this flow will lead to different senses being activated. So our reaction depends on the activation of these senses.
Teaching the subjects in this manner will open up a whole new vista for the children. Science teachers can re-look at the way we facilitate learning of the subject without sacrificing the pressure of completing the syllabus. What we need is more interaction and trust between the teachers themselves. If the teachers discuss among themselves it will also help them think out of the box and do more research, which will contribute to their own development. It will also contribute to the development of critical thinking and problem solving skills among the students.
Between physics and biology
Linear elasticity
When you apply force to an object, it experiences displacement. But once the force is taken away, the object returns to its original position. This is called Linear elasticity. In the case of non-linear elasticity, the object does not return to the original position when the force is removed. This can be explained using the muscles of the human body. When force is applied to the muscles, they stretch (linear elasticity). But they also have a “breaking point” or elastic limit. If force is applied beyond this point, the muscle will experience a strain or sprain. This occurs due to a non-linear or an unbalanced force acting on the muscle. For the muscle to return to its original position, it requires rest and medical attention. However, in the case of a spring, if the elastic limit is reached, it is a point of no return.
So if teachers are able to connect Hooke’s Law with the working of human muscles, the connection between physics and biology can be easily understood. Worksheets can be created showing both a spring with weights hung on it and images of a muscle strain or stretch and ask related questions.
Source: https://prezi.com/fpsmealyjy4y/hookes-lawin-the-humanbody/
Electrical circuits
The nervous system in the human body is similar to electrical circuits. When the impulses are transferred to the brain, it sends out instructions to various parts of the body using the blood stream. This is similar to the electrical circuits sending electrical impulses through the wires. Both the electrical circuits and the nervous system have some sort of load. For the nervous system, the muscles and the organs act as a “resistance”. Both use a power source: for the nervous system, it is the sodium and potassium molecules available in food. The resistance in the human body is comparable to light bulbs, the batteries, transformers and other resistances in electrical circuits. For example when a human being has a paralytic stroke, it disturbs the free flow of impulses in the body leading to complications. This is similar to short circuiting of electricity in wires.
So the teacher should encourage children to read from books and to discuss in class the connections between the two subjects. The teacher can also ask the students to refer to websites similar to the website id given below.
Source: https://prezi.com/msu6gppdus1c/nervoussystem-and-electric-circuit/
The author is the Academic Director at Vidya Vanam in Anaikatti, a school for tribal and underprivileged children. He has nine years of experience in teaching and has been actively associated with Vidya Vanam for the past three years. He can be reached at srikanthtm@vidyavanam.org.