Lab Activities
InTASC Standard 8: The teacher understands and uses a variety of instructional strategies to encourage learners to develop deep understanding of content areas and their connections, and to build skills to apply knowledge in meaningful ways.
Introduction
Lab activities are by far the most popular instructional strategy I implement in my classroom. Student engagement levels are at their highest on lab days. For this reason, I strive to incorporate at least one lab per week. This strategy can be used in a variety of ways to encourage students to develop deep understanding of all chemistry content areas. Labs can be used to introduce new material, practice previously learned concepts, see concepts come to life with first-hand experiences, replicate historic experiments, integrate technology and student interest, review concepts and assess student knowledge. Each of these different situations allows students to take theoretical concepts learned in class and apply them in authentic and meaningful ways.
Purposefully Assigned Lab Groups
Kagan-inspired table group chart
Students are assigned to lab teams of four, based on Kagan’s method for collaborative grouping. This method consists of placing four different “levels” of student, in regards to achievement, in each group—each having a ‘high,’ a ‘medium-high,’ a ‘medium-low,’ and a ‘low’ student. By having each of the four “levels” of students at each table, it allows for maximum support. The students with higher levels of knowledge can support the students who are struggling to access the content. The ‘high’ student also benefits because they will occasionally have to explain a concept to their partner. Research shows the best way to learn a concept and retain it in long-term memory is to teach it to someone else. Conversely, the ‘low’ students have someone at their table they can ask for assistance if I am personally assisting a different group. This structure maximizes learning and holds all students accountable to their partner. These groups change every unit to encourage the development of strong collaborative and interpersonal skills.
Each table has a modified Kagan table group chart—shown in the picture on the left—that allows me to easily assign roles during labs and other classroom activities. I can also use these charts and assigned seat numbers to easily divide tables further into partner pairs when necessary.
Team Building Activities
Each time students are assigned to new collaborative table groups; we do a team building activity. Often these are just quick activities at the beginning or the end of a lesson. These are designed to allow students to get to know their new team members and start to get comfortable working together before introducing new content. One example of this activity is the marshmallow challenge—pictured on the left. Students are given 20 raw pasta noodles, one meter of tape, one meter of yarn, and a single marshmallow. They are informed they have 30 minutes to get the marshmallow as high off the ground as possible—using only the provided materials. The team whose marshmallow is the highest when time is up wins. No further instructions are provided and I tell students they are not allowed to ask me questions for the duration of the activity. This specific activity is introduced as our first lab and has several secondary aims in addition to team building.
Students must immediately become comfortable with each other to successfully work within their collaborative teams. They need to communicate ideas clearly and make quick decisions. Not being able to ask me questions also pushes them to ask each other for help and shows them that their classmates have valuable thoughts to add to conversations. In addition, in order to win the challenge students need to be out-of-the-box thinkers and get creative with their structures and their ideas. Through all of my classes, I have seen some innovative solutions to this activity—including flipping a table on its side to start from a higher surface and hanging the marshmallow from one of the pipes that runs along my classroom ceiling. We conclude this activity by having a discussion about all of these skills and how they can each be applied to actual content-based labs as we move through the course.
Students building their marshmallow structure
Technology Integration
Student work for the online "Build an Atom" Lab Activity
Access to technology at my school site is sporadic at best. There are laptop carts, but they can be difficult to obtain. There is also a computer lab, but it is nearly always reserved for various testing. Despite this, I make every attempt to allow my students access to technology as often as possible. The effective use of technology is a 21stcentury skill that will be crucial for future success for our students and I strive to provide ample opportunities to develop this specific skill set.
Lab activities can be an effective tool to reteach concepts that students need additional support with to obtain mastery. Through formative assessment data I determined that students were struggling to develop a deep understanding of the structure of an atom. Not being able to properly visualize the atom and subatomic particle was blocking students from understanding the content. Since we cannot physically see an atom, students did an online lab activity—with the procedure shown in the document on the left—where they could manipulate an atom simulator. Students could add and remove protons, neutrons, and electrons and see how each impacts the various properties of the atom.
Historic Experiment Replication
One issue that has the potential to block many students from developing a deep understanding of chemistry content—especially atomic theory—is that much of what we discuss in class cannot actually be observed. For example, in regards to the structure of the atom, we must trust that the information we have at our disposal is accurate. While we can examine the experimental results of historic scientists, typically these experiments cannot be replicated in a high school classroom environment. Understanding atomic structure requires a leap of faith on our students’ part.
This topic presents another issue for instruction because students must learn about all the scientists that created incorrect models for the atom before we can learn about the current model—which one-day will also most likely be proven inaccurate. The first time I taught Rutherford’s gold foil experiment, I found that while students could state what he did they did not actually comprehend how he came up with his results. For this reason, I implemented a lab activity—shown on the left—to give students first hand practice with Rutherford’s methods and the probability calculations he used to discover the size of the nucleus.
Students participating in a modified replication of Rutherford's historic experiment
Lab procedure, student-obtained data and post-lab analysis for the Gold Foil Lab
Rutherford shot alpha particles at gold foil and tracked the angles at which each particle was deflected. He used this data to determine that the atom was made up of mostly empty space with a dense, positively charged center. This experiment can obviously not be recreated in a classroom. I attempted to show a video of the experiment but this was not of interest to students. Instead, I modified Rutherford’s experimental procedure to use a more common item—marbles.
Students set up a track with a start and finish line, as shown in the picture. They then place five marbles along the finish line. Students stand behind the start line and roll a marble towards the finish line—counting how many times marbles collide and how many times the marble rolls straight through. After 100 rolls students complete various calculations—shown in the document on the left—to see if they can determine the diameter of the marble. This answer is then compared to the measured diameter. Students then compare this lab activity to Rutherford’s experiment. By getting hands on experience with Rutherford’s methods, students are able to develop a deeper understanding of how the current model for the atom was designed.
Ionic and Covalent Bonds Labs
Lab activities can also be utilized after guided notes and direct instruction as a way for students to develop a deeper understanding of the content covered in class and how this content connects to the real world. The two labs shown below act to reinforce the concepts of ionic and covalent bonds and allow students to apply their content knowledge in meaningful ways.
The document shown on the left—the “Salt Lab”—consists of each lab group starting with baking soda and hydrochloric acid and creating sodium chloride—table salt—through an experimental procedure. This lab directly follows our notes about ionic bonding and the post-lab analysis questions act as a way for students to show mastery of previously learned content through use of experimental data and their first-hand experiences in the lab.
"Salt Lab" procedure and post-lab analysis questions
Instead of just comparing the properties of covalent bonds and ionic bonds, students complete the “Salt & Sugar Lab” to practice these concepts first hand. Covalently bonded molecules, when dissolved in water, do not conduct electricity. Ionically bonded compounds, when dissolved in water, do conduct electricity. Also compounds have higher melting points then molecules. This lab—as seen in the document on the left—was designed to give students the opportunity to see these concepts in common household items. Students also completed several post-lab analysis questions to display mastery of the content learned in the lab.
"Salt & Sugar Lab" procedure and post-lab analysis questions
Acids and Bases Exploration
Lab activities can also act as an explore activity or introduction to new material. Acids and bases are often referenced in popular culture and students enter my classroom with a preconceived notion about these substances. However, students rarely have an actual understanding of the scientific definitions of “acid” and “base,” and the properties of each of these substances. Acids and bases are all around us and this lab was designed to show students that what we are leaning in class is linked to products they use in their daily lives.
At the start of our unit about acids and bases—before any direct instruction or explicit introduction of new material—students conduct this explore lab. As students enter the classroom, the materials for the lab—shown in the picture on the left—are on the table in the center of my classroom. These are mostly common household items that students are familiar with—lemon juice, milk of magnesia, hand soap, orange juice, baking soda, vinegar, crushed antacid tablets, and diet Dr. Pepper. A mystery solution is also included—a hydroponic solution that was created and is used by myself and another chemistry teacher in our community garden.
Lab materials for the "Acid/Base Explore Lab"
Data collected during the lab activity
The goal of this lab—shown in the image on the left—is to allow students to conduct various tests on acids and bases to attempt to determine common properties before we discuss them in notes. This grounds our notes and learning in real world application from day one of the unit. During the lab, students will touch each of the substances. They will then taste each—with the expectation of soap, which I tell students tastes bitter. Solution six—bleach—has been omitted because, when I conducted this lab when I was in high school myself, I accidentally drank our sample of bleach and had to go to the hospital. To avoid a similar situation, we conduct a discussion about what the properties of bleach would be based on our other data at the end of class. I also tell students this story and they tend to enjoy that I did this lab when I was their age. After tasting each solution, students use a pH meter and an electrical conductivity meter to determine these data points. Finally, students use phenolphthalein drops and record the color the substance changes. By the end of the lab students have a partial rainbow of colored samples. Finally, students are asked to try to sort the substances into different categories based on their experimental results. We then use these lists as our starting point for our explicit discussion of the properties of acids and bases in Lesson 5.2 Guided Notes—shown previously in the “Organizational Aids” section.
Student Interest Labs
The first instructional segment of the Next Generation Science Standards has a theme of combustion and calorimetry. I realized there was a simple way to link this overarching key concept to students’ interests and make the unit significantly more applicable to their daily lives. Nutrition is a significant issue for students at the school in which I teach. My school is located in a food desert and students have limited access to fruits, vegetables, and other healthy food options. While nearly all of my students are on a free and reduced price lunch program and breakfast is provided in the classroom every morning, most students do not eat this provided mostly-healthy food—opting to eat a bag of Hot Cheetos or Takis as a meal replacement. Telling students that these, arguably delicious snacks, are unhealthy has little effect. Instead, the first unit in my class has the theme of “How Many Calories Are Really in a Bag of Flamin’ Hot Cheetos” to show how unhealthy this food choice is.
We begin our unit with an article about the obesity epidemic in the US—student sample located in “Literacy Integration.” We then go through all the various aspects of the unit, learning about calorimetry and relating all topics back to Hot Cheetos and health. This lab—which students are conducting in the picture on the left—happens towards the end of the unit and allows students to synthesize knowledge and display mastery of concepts and calorimetry calculations learned in class. Students build a calorimeter, obtain experimental data by burning Hot Cheetos, practice calorimetry calculations to determine the amount of calories present, compare these with the nutrition label on the back of the bag, and finally complete a post-lab analysis and reflection.
Students participating in the "Hot Cheetos Lab"
Lab procedure, calorimetry calculations and post-lab analysis for the "Hot Cheetos Lab"
Furthermore, many of my students struggle with foundational math skills and need additional support when math concepts are used. These students tend to entirely shut down and not try if given independent practice involving mathematic calculations. If I would hand out a worksheet practicing math relating to calorimetry, engagement would likely be very low. By experimentally relating this practice to Hot Cheetos—in the lab procedure on the left—student interest and engagement is significantly higher because students actually want to see if their experimental data and calculations match the number given for calories on the nutrition label on the back of the bag.
This is one of my favorite labs of the year because it typically has a visible impact on my students. When you burn a Hot Cheeto it burns brightly and begins to melt. Eventually all you are left with is a shriveled black crisp surrounded by a puddle of disgusting oil. Students tend to get incredibly grossed out. We then discuss that this is a food they are voluntarily putting in their bodies on a daily basis. Students can see a link between the gross, black, charred Cheeto and the health concepts—such as oily skin, acne, obesity, lack of energy, etc.—that we have been discussing in class during this unit. It makes my day every time I see a student grab an apple from the breakfast cart instead of pull a bag of Hot Cheetos out of their backpack.
Reflection
Through experience, I have learned that this is one of the single most powerful instructional strategies I can implement to encourage my students to develop a deep understanding of content. Experiencing concepts in a hand-on activity allows students to take content knowledge and apply it in meaningful ways. I am always researching new labs to be implemented in class for primary learning experiences, re-teaching, review, assessment and additional practice.
Furthermore, whenever I give students a feedback survey I get several hundred responses along the lines of “do more labs.” We could do a lab every class period and I would probably receive this same feedback. Lab activities are the best part about being a chemistry student and a chemistry teacher and I try to utilize them as often as possible.