Chemistry is a laboratory science and can be most effectively taught by including robust hands-on laboratory experiences for students at both the middle and high school levels. This perspective reflects one of the core principles of the Next Generation Science Standards: the idea that students can learn content by engaging in scientific practices.
The identification, manipulation, and general use of laboratory equipment are integral parts of the subject. Where resources allow, the school laboratory should have equipment to conduct meaningful demonstrations and experiments (see a full list of recommended equipment in the Lab and Safety Equipment section). The laboratory environment must be accessible to all students and maintained with safety in mind. Teachers should use safety measures to protect students and themselves during any investigation. With appropriate accommodations, students with disabilities can participate in the laboratory experience.
Three Phases of the Lab
Instruction that is student-centered, hands-on, and emphasizes the role of laboratory demonstrations and experiments is the best method to ensure that students develop the essential skills of science. Laboratory investigations should come in three phases: the pre-lab, the laboratory experience, and the post-lab.
Pre-Lab
In the pre-lab, students should consider the concept or principle to be investigated. This gives them the opportunity to make predictions and hypotheses. Effective pre-lab questions can prompt students to review and recall previously learned concepts that are pertinent to the investigation. This is also an opportunity to discuss safety protocols for the laboratory and introduce any new laboratory equipment they will use.
Lab Experience
The laboratory experience allows students to learn how to plan their actions and to identify and control variables. During the investigation, they will observe, measure, classify, and record data. They must conduct all labs following safety guidelines. Incorporating technology into laboratory investigations may enhance how students collect and manipulate data (see the Technology in the Laboratory section).
Post-Lab
The post-lab provides an opportunity for students to analyze and interpret data, evaluate the effectiveness of the procedure, formulate models, and communicate their findings in written and oral formats. Students can also relate or compare results and concepts with classmates and previously learned phenomena. It’s important to emphasize during this part that collecting the same data does not mean final reports will be the same; there’s a difference between collaborating and copying. Each student will grapple with the data a little differently and express their findings using their own voice. The post-lab is also a time for students to evaluate the safety guidelines that were presented in the pre-lab.
Download the Three Parts of a Lab infographic.
Same Reaction, Multiple Lessons
Some laboratory experiences can be used in a variety of teaching contexts. For example, carrying out the simple reaction between CuSO4 and Al illustrates many concepts of chemistry:
- Chemical change
- Single replacement reaction
- Redox chemistry
- Activity series
- Solubility
- Concentration
- Conservation of mass
It can be helpful to repeat this reaction multiple times throughout the year to show students that the reaction always has the same outcome and shows evidence of many types of chemical phenomena.
Optimizing the Laboratory Experience
The laboratory experience is an opportunity for students to test scientific hypotheses, and not simply verify predicted outcomes. In this vein, do not hesitate to repeat experiments. Focus on different aspects of the reaction through a different lens so that students can understand a new concept.
It is often appropriate to begin a unit with an investigation (especially discovery-style activities). This creates a concrete and unified example that students can relate to as they study concepts throughout a unit. Laboratory work should be an integral part of the curriculum and appropriately fit into the lesson structure. Labs should not be done merely for the sake of doing them; students should be able to draw a conclusion from the investigation that relates to the concepts in the unit.
Middle school chemistry classrooms can function very much like those in high school, even without dedicated laboratory stations. Simple household materials and safe kitchen chemicals can be used to foster inquiry, gather data, interpret results, and explore phenomena. The site www.middleschoolchemistry.com provides a comprehensive curriculum with videos, simulations, demonstrations, and labs that are age-appropriate.
Many resources are available for planning student-centered laboratory instruction:
Additionally, ACS publishes a variety of books and magazines for chemistry students of all ages. The National Science Teaching Association (NSTA) offers many resources about laboratory investigations in the chemistry classroom. Most science supply companies, including Flinn Scientific, Carolina Biological, Sargent Welch, and others, have many laboratory and demonstration materials available for purchase.
Teachers can help students continue to expand on chemistry concepts outside the classroom. One core strategy is to encourage interested students to participate in afterschool programs that will give them opportunities to demonstrate and deepen their understanding of chemistry. Other examples include starting an extracurricular club or applying for internships with local companies, universities, etc. For more ideas about engaging students in chemistry outside the classroom, see the Chemistry Resources and Extracurricular Activities section.
