This is the first lesson in a unit about the atom. Students will watch a fun music video that explains what the elements are. They then do some reading and note-taking about elements and atoms. Finally, they use a data table to learn about how many pounds of each element exist in their bodies.
This lesson aligns to the NGSS Cross-cutting concept of Patterns because it begins to ask students to think about how matter is comprised. It also aligns to the NGSS Science and Engineering Practice of Using Mathematics and Computational Thinking by introducing students to the concept of a spreadsheet as a tool for conducting multiple mathematical calculations in an efficient manner.
This lesson assumes students' basic understanding of how to use a computer but otherwise does not rely on prior knowledge. It assumes that a teacher knows how to distribute documents electronically and has a basic understanding of how to use a spreadsheet to conduct simple arithmatic.
Do Now: Students read a short article about atoms and elements. I use page 42 in our text book, A Natural Approach to Chemistry. A more complex article that gets at the same material can be found at the ChemWiki website. In their notebooks they record the definition of the word element. They then try to explain how elements and atoms relate to one another. I do not expect all students to immediately understand this second part, but I want to give students a chance to begin grappling with the day's topic. This is part of our class routine; every day when students enter the classroom they have a "Do Now" waiting for them, projected on the screen, along with the homework, the page numbers in the book, and a learning objective.
Activator: After students have had a chance to complete the Do Now, I tell them that I am know going to show them a very technical video about elements. I then show a video from the band They Might Be Giants, called Meet the Elements. They laugh at my characterization, and then enjoy the video. Some students start singing the chorus by the end of the song. I choose this song because it is fun, but also because it does a good job of making an analogy about the elements, calling them a box of paints that can be used to create so many different things. The video is a little silly, too, which helps to put some students at ease in a class that has a reputation for being difficult.
Part 1: I cold call to ask students to share their ideas about the Do Now prompts. I get a variety of answers. One analogy that keeps coming up is the idea of elements as ingredients for matter. The connection that is difficult for students to make is that elements are types of atoms. I explain that in this unit students will learn how different elements have different atoms, and we will learn how the elements are different.
For context, I want my students to understand the atom's place in the scheme of things. Here is a video of me teaching about the scale of the atom using a series of slides from this website. I think that it is important for students to understand how the atom is related to things we already know from everyday experience, such as a leaf.
I then explain that as a starting point I would like them to learn the location, name, and chemical symbol of the first 20 elements. We focus on the first 20 elements because these are the elements we will focus on when we learn about the structure of the atom. We will focus on the s and p orbitals and the first 20 elements only contain these.
I explain what I mean by "first 20 elements" by showing them how each element has an atomic number, the whole number found above the chemical symbol. I note that the chemical symbol is a 1-2 letter code for the chemical. Some of them are really obvious, such as O for oxygen. Some of them, like Na for sodium, are less obvious because they are named from the Latin word for sodium carbonate, natrium. I then spend some time asking students to share strategies for memorizing information. Here is a list that we come up with:
Use flashcards and quiz yourself until you know them.
Come up with sentences where the first word in each sentence represents one of the elements: Hector Helps Lift Because Bobby Can't
Put the elements into a song, or find one on the internet. My students use this one, among others.
Over the years some students and parents have suggested that memorization is not learning. As a college-bound school, I note that there are many different kinds of learning. Certainly we do not focus solely on memorization. However, I note, colleges rely heavily on a student's ability to memorize information as a key indicator of whether a student earns credits in a course. As for me, I tell them, I would much rather be operated on by a surgeon who has memorized where the parts of my body are. Many of my students are not used to memorizing, but when they put their mind to it they are able to do so.
The teacher-guided lesson pauses for ten minutes and students begin work on this.
Part 2: After students have practiced for about 10 minutes I switch gears. I remind them that all matter including humans, are made of elements. I explain to them that today we are going to calculate how many pounds of each element exist in our bodies. I pass out a printout of the spreadsheet Percent mass of elements in human body for their perusal. I instruct each student to weigh themselves on a scale that I have brought in. I also ask each student to sign out a laptop from our cart, and to go to our class website to download an electronic version of the spreadsheet.
Once all students have done this task, I teach them how to calculate pounds of each element using percentages. Many students do not know that to calculate the amount of oxygen, they have to multiply the percentage by their weight and divide by 100. I show them this, and then instruct them to start doing this work on the paper copy of the spreadsheet.
This is a useful exercise for two reasons. First, it is engaging, and students can connect elements to themselves in a personal way. Second, it teaches students valuable data analysis skills that can be transferred to other contexts, such as percent composition of compounds.
Part 3: Once the tedium seems to be setting in (after students have filled in several rows, I tell them that I can complete this spreadsheet in about 1-2 minutes. They look at me incredulously, and we banter. I explain to them that one purpose of a spreadsheet is to quickly conduct calculations. I teach them how to conduct a calculation using Excel, and then I show them how to drag on Excel so that they can complete the entire column. I show them how to "sum" their work and explain that the sum should equal their weight.
Part 1: After teaching about chemical name, chemical symbol, and atomic number, I ask students to work on beginning the process of learning the 20 elements. I tell students that research shows that deeper learning will happen if they look at and practice the material over several sessions rather than just over one session.
Part 2: Students manually complete the spreadsheet so that they are calculating how many pounds of each element are found in their bodies.
Part 3: Students use the spreadsheet to quickly finish their calculations and check their work. Due to rounding, the weight of the student does not always equal their weight, but it is always close if students have completed the spreadsheet properly. Here is a completed data table for a 150 pound person.
I based this portion of the lesson from this website.
At this point I want to capture some of the main points from this lesson. The following question and answer period ensues. I use cold call to randomly call on students to answer these questions. From this quick data collection, students appear to know most of the answers, but they need more help in understanding the relationship between element and atom, which is a topic we can return to in subsequent lessons.
What are elements? (materials that make up the universe)
What are atoms? (pieces of elements; the smallest amount of an element)
What elements do I want you to know? (the first 20)
What do you need to know? (atomic number, element name with correct spelling, and chemical symbol)
What is a spreadsheet good for? (quick calculations)
Who is faster in conducting calculations--me or you? (we are)
What are some of the main elements that make up the human body? ( C, H, N, O)