What Science Should We Teach?

07/15/2015  |  Dr. Tom Hsu

If we tried to teach everything we are asked to teach, very few students would be able learn all the material in a typical grade’s science curricula. This is especially true considering we have only 36 weeks, and would still be true if we had twice that much time. That doesn’t mean we couldn’t teach it. Teachers are pretty good at working under impossible conditions; we can teach anything. The students just wouldn’t be able to learn it all. Which brings me to my title; what science should we teach? Within the vast body of scientific knowledge and skills, what is most appropriate for k-12 students? What is learnable, teachable, important, and relevant? What, out of the teachable and learnable subset, fits into our standards and assessments?

You love science! I love science. We each find our specific area of science fascinating, and long ago learned its language and customs. To help our students learn we all need to take the difficult but necessary step of moving to the other side of the desk, to stand in the shoes of someone who does not speak our language, does not know endoplasmic reticulum or molarity or periodic force. Someone who does not care at all that the quadratic formula is beautiful.  Then we need to go outside the school system altogether. What knowledge and skills will help our students succeed in fields other than research science?  Many fewer than 1% of students ever become research scientists. Should our curriculum be driven, as it is, by the purpose of preparing research scientists? 
I became successful because of public schools. I can still remember exactly when I decided I liked science. In the sixth grade my teacher did a science lesson on paper airplanes. She brought in a student from a local college to help and he showed me different ways to make a paper airplane fly. Then they both helped me learn to make it fly even farther. I was hooked; I wanted to build airplanes and eventually went to college to study aerospace engineering. I was hooked because:
•    The curriculum was made meaningful to me.
•    I had a positive, successful (carefully structured) hands-on experience
•    I got to do the real stuff, building an airplane, without lots of theory. Later, I wanted to learn the theory!
I know airplanes were not in the science standards for 6th grade. At that time there were no science standards. It was a lesson my teacher had been successful with, she felt good about teaching it, and she knew it would be engaging. I am thankful she did what she knew was best. It made a difference and was a pivotal event in setting my life in its current track. In all my experience since, I find science everywhere. What I know of science has helped me succeed in every single job I have ever done, from cooking to business to research. The high school course I value the most was metal shop, a course I took in the 8th grade. I remember begging my overworked guidance counselor to allow me to register for this non-academic, vocational class. That course taught me that I could build anything my mind could conceive. The rest was training my mind to conceive of interesting things!
At Eastman Kodak, where I once worked in engineering, we had an informal prize whenever one of us needed to use calculus in our jobs. We awarded it only once during the several years I was there. I challenge you to think about each topic in your curriculum as it applies to success in real life, outside of science. You will find that many ideas in “standard” curriculum are not useful! Maybe they were once useful, but no longer. Maybe they are useful to research scientists, but so what! We spend inordinate amounts of our precious class time teaching many concepts that are important to no one but specialists in our discipline. They are not bad concepts to teach. But what are we neglecting in their stead?
I believe the mission of k-12 science education is to give all graduates of high school useful scientific and technical knowledge and skills. By “useful”, I mean the things they can use in their lives, outside of laboratories and outside of science education. Leave the universities to train the research scientists. We need to prepare everyone else; the business people, the contractors, and most important the future parents, to understand how our technical world operates. People have a tendency to fear and mistrust what they don’t understand. America became great on the basis of our technical and scientific prowess. We need to keep that torch burning by making sure all Americans are able solve problems and make informed technical decisions based on sound scientific knowledge and reasoning.
Physics First
As you may know, there is a strong movement to put physics first in the high school curriculum followed by chemistry, then biology. Being a physicist, naturally I think of physics as the most important science, right? Wrong. The drastic changes in human society that came with the agricultural revolution (2,000 years) the industrial revolution (300 years) and the information revolution (40 years) will pale before the changes that will come as we explore our ability to change our very species itself and the detailed workings of our planet. If the wrong microbe were to get loose homo sapiens could become extinct far faster than the dinosaurs. 
I agree with the physics first initiative because physics is the easiest way to teach systems thinking and quantitative reasoning. I believe traditional biology with its overemphasis on classification and vocabulary fails to adequately prepare students to understand their role in the larger ecosystem of Earth or even the functions of their own bodies. To understand molecular biology you really need a foundation of chemistry. And to understand why chemistry occurs you need to understand energy, atoms, and systems. That is why physics should be first: because it is the most direct way to teach the big ideas of energy, atoms, causality, and systems. Physics provides the foundation for chemistry which is the foundation for modern biology.
I believe the most important role of science in k-12 is in enabling people to understand the bigger picture of complex systems, such as biology and ecology. When our students grow up (literally, not figuratively) they will decide how to apply genetic engineering to the food chain, to the natural world, and to our species. I really want those decisions made with rational forethought and with consideration of the future rather than the next fiscal quarter.
This said, throwing the traditional wall of "physics" math at eighth and ninth graders will NOT get us where we need to be! Physics First needs to be a different physics than was Physics Last (or no physics). A ninth grade physics course must develop the big ideas of systems, energy, and atoms conceptually and mathematically, with the concept preceding the math and not vice versa. Energy conservation is such an important idea that it should not wait until mid-year. Many traditionally important results, such as free fall, and mechanical advantage can be developed using energy arguments far easier than with traditional vector algebra. We need to rethink how we teach physics as well as what we teach to develop a sound foundation of both understanding and quantitative thinking. 
I am a strong believer in guided inquiry. In guided inquiry a group of students is presented with a phenomena, offered some pertinent questions and a suggested path of inquiry that might lead to an explanation. We developed some very special experiments that create situations that are easy to describe and reproduce, yet deep in understanding. For example, imagine a track that starts with a downhill slope followed by a level section about as long as the slope. A little car starts from the top of the hill, rolls down the hill, along the flat, and then bounces off a rubber band at the bottom. After bouncing, the car then rolls backward and partially up the hill again. Students notice that the car never rolls back as high as it started. Why? What is the explanation for why the car never goes higher than it started? Energy of height (potential energy) is proportional to height. Energy of speed (kinetic energy) is proportional to speed. The car never rolls back higher than it started because that would require more energy than is available. 
Once students see the big idea that the car needs more energy to get higher, we pose the next question: is there any way the car can be made to go higher than it starts? If so, how, and why? Once they are thinking in terms of limited energy, students quickly realize that they need to give the car more energy. For example, a small push downwards at the start gives the car additional energy. Pushing adds energy and the car can now roll higher than it started. By using a real car and track, students learn almost immediately about efficiency. Friction diverts some energy and it takes a substantial push just to get the car back to its initial height.
The guided inquiry approach is powerful and effective when the curriculum and equipment are developed to work together. You wouldn’t want your surgeon operating with a kitchen paring knife would you? A scalpel is specifically designed for surgery and the experiments should be created specifically to learn and not merely to demonstrate! Just as a scalpel is more than “a sharp knife” the effectiveness of a real car and track as a learning tool is based on designing the actual car and track to have just the right kind of friction, the right sorts of angles, the right kind of wheels and bearings, a technique for applying a controlled force, a way to measure level, and countless other details. You just can’t get this kind of deep learning to happen with sticks and strings. Actually you could, but few of us have Galileo’s talent, patience, or time!   
I believe we cannot teach some of the content in many science standards in a way that most of our students will learn it and retain it. That means we must choose which content to teach and which to ignore. Why not choose what to cover based on what we teach well and what we think students can learn? We favor the use of some very practical questions when choosing what to emphasize in a curriculum. 
Question #1: Is there a useful application of this concept, outside of academic science, that students can understand at the level they are at? If there is no such an application, or the application is incomprehensibly advanced, you should think very hard about teaching a different concept instead. There is plenty in the curriculum to choose from!
Electricity provides a good example of how to apply rule number one. To most of the world, the important aspects of electricity are voltage and current. Voltage and current are the things we use every day when we plug in appliances or turn on a light. Current is what flows and does work. Voltage measures the available power that is carried by a quantity of flowing current, such as one amp. One amp of current from a 120 volt wall outlet carries 120 watts of power to do useful things. 120 watts can propel a bicycle and rider up a moderate hill. The same one amp of current flowing out of a 1.5 volt battery carries only 1.5 watts of power. 1.5 watts is barely enough power to light a night light; not nearly enough to ride up a hill. The amount of current is the same. The voltage tells you how much power each amp carries. Voltage and current are real, measurable, every-day concepts students can measure and use. We build circuits, make light bulbs glow and only then, once the student has some successful experience and, only then do we ask what is really going on inside those wires. Then is the time to learn the more abstract concepts of electric forces and fields. We call this the STEM approach. We use practical applications of engineering and technology (amps and volts) to teach the science of physics (electricity and magnetism).
Consider the fact that virtually every traditional physics course begins the same topic of electricity with electric charges, the electric field, and Coulomb’s inverse square law of the force between two electric charges. Almost no one outside physics uses Coulomb’s law or cares that electrons really move from negative to positive. In many books the short (and inadequate) section on voltage and current is at the very end of the unit. Many (if not most) physics teachers never get to the end of the unit and therefore the majority of students never learn the practical application of electricity. Why do physics courses start with the abstractions of charges and electric fields? We call this the "anti-STEM" approach! The anti-STEM approach is to subtract all practical engineering and technology from the teaching of "pure science." 
Question #2: Does the concept help build understanding of the big picture or is it a small detail? 
I have seen a k-12 science curriculum that teaches density for two weeks, every year, in every grade, from grade 4 to grade 9. In the grand scheme of things density is a tiny detail. Its emphasis in the curriculum is far in excess of its importance. Physics is no better at prioritizing content. Fully one quarter of a traditional physics book is devoted to building up the equations of accelerated motion. There are subscripts, superscripts and symbols; there are diagrams and frictionless examples; and there are difficult-to-parse word problems that carefully construct situations of constant acceleration. Do you know that in the real world there are virtually no situations of constant acceleration! Students must survive a half-dozen chapters before they get to the really important and useful ideas of energy and systems. 
Question #3: Is the concept important today, or is it only historically important? 
Unless the historical development is really important to understanding what is useful today, we skipped it. We want students to learn science that they can use today, not science that was interesting 100 years ago. History is important, but not as important as having a scientifically literate population who can evaluate scientific issues rationally.
Question #4: How can you teach this concept while introducing the fewest number of new words or equations required to learn and use it? 
This is hard for us since we know the language and customs of our scientific disciplines. Try marking out every word not in common use and see if you can still teach the big idea. The average educated person’s vocabulary is around 20,000 words. The average 9th grade biology book has more than 2,000 new words; words that a student must decipher to be able to understand the important ideas in the book; words that will never be used again outside the narrow world of research biology and medicine. Can we teach the ideas without this incredible barrier of words? For example, I have seen the term “endoplasmic reticulum” on an 8th grade state assessment. Why is this term there? In my humble opinion you can teach the important ideas in biology, such as ecosystems, food chains, anatomy and physiology, heredity, evolution, and the organization of life on Earth, without 90% of the big words. Wouldn’t you rather have students understand the important ideas instead of the specialized vocabulary?
Question #5: Is there a way for students to get hands-on experience with this concept? 
Teaching the mathematical representation of electric fields (Coulomb's law) to ninth grade students is almost a waste of time. Students have neither the mathematical skills, nor the experiential background to understand and use the concepts. Unless you are willing to invest the time in providing experiences to give kids a handle on the abstractions, don't hold students responsible for learning material that can only be understood using mathematics above your students heads. That doesn't mean your shouldn't talk about cool things like time travel or quarks! It just means that "engagement topics" such as relativity should not be on the test, and students should know that they are not responsible for understanding time travel. 
Technology is a great way to introduce concepts in science and make them relevant. For example, instead of starting a sound unit with the theory of waves, why not start by asking how a CD works? 100 years ago you could only hear music if you were next to a musician! Very few people heard enough musicians to even have a favorite band. The recording of sound was tremendously important to the development of culture, and engages kids. Exactly how do you capture a sound and record it so it can be played back? You probably can’t find a kid today who does not know what an MP3 file is. Do you know what an MP3 file is? How is it different from the sound recorded on a CD? The technique of starting with technology is interesting and engaging to students, I have done it many times. The other way (theory first) is boring to most students; I have done that too!
I should warn the reader that while I am expressing one personal opinion many of these ideas have come from other teachers across America. It has been my pleasure to have taught, and worked with, more than 18,000 teachers over the past 25 years, both in workshops across the country and in courses I have taught. Over time, I developed some of these rules from my own classroom teaching, in urban and suburban schools, public and private, with students ranging from fourth grade through graduate school.
Some of my critique of "pure science" comes from a background of practical engineering. Even in my "research" career I liked to build things, first at the superconducting accelerator at Stony Brook, and later on the Alcator tokamak fusion experiment at MIT. My work in industry including developing the first color copiers (Xerox, Dupont), manufacturing photographic paper and film (Kodak), manufacturing science equipment and publishing books (first with CPO Science and now with Ergopedia). 
At heart, I am a teacher. When people ask me what I do, I proudly inform them that I am a science teacher. When asked how I got that way, I said that my own teachers made a huge difference in my life.  My father was a cook and my mother was a waitress. I grew up in public schools, and along the way have been a carpenter, a cook, an engineer, a bicycle mechanic, a nanny, and even a musician (although, to be honest, I never actually earned any money as a musician).  Every one of these experiences has enriched my ability as a teacher.
When I started teaching in a public school, I taught carpentry and physics to inter-city vocational students. I had a dream that if students could build physics experiments with their own hands, they could also learn how those experiments worked. I taught my students to build wooden roller coasters, cars and ramps, and other such things. After overcoming my start-up mistakes, the program actually worked. My “low prospect” kids, all of them minorities, won the science fair a year later, competing against the academic kids. Of course, we could build our catapults out of brass and mahogany because we had good tools! My mistake was calling the course “Craft of Science”. Nobody, except me and my headmaster, knew what that meant. I got a lot more respect (and so did my students) when I changed the name of the course to “Introduction to Physics and Engineering”. Of course, I still taught the exact same thing, but I learned a valuable lesson. 
As far as the big test goes, every study I have read says the same thing. If you teach less and teach it deeper, kids do better overall. When it comes to covering content, less is more. Kids do better because when you go slower, material they know, they really know, and can prove it on a test. If you skip, ankle deep, through a wide field of content the students really retain very little about anything. Shallow knowledge leaves students easily confused and not able to show what they do know. To get a "highly proficient" score on a standardized test you need to answer somewhere around 75 percent of the questions correctly. An average passing score is around 55 percent on almost any high stakes assessment. My recommendation: find the 75 percent of the curriculum that you teach well and have successful methods for, and teach that. Forget about the rest. Next year try changing which 75 percent you teach. That way you get to learn too, and develop new lessons.
There is nothing wrong with applied science! In fact, recognizing this, most states have adopted technology and engineering standards in the NGSS. These are usually treated as a separate area of the curriculum, and almost always neglected. This is a mistake! If we had waited until we understood the equations for stress and strain we would never have built the cathedral of St. Peter or the great wall of China. We learned fundamental science by doing technology. We should teach our students in the same way. We should not assume they will make the connection between the abstract ideas in their science books how that science is actually used. By technology, I don’t mean computers. I mean the application of knowledge about how nature works to solving human problems.


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