Chemistry Solutions

Throughout my 33-year career, it seems the one constant in education has been change. That being said, there is the old adage “the more things change, the more they stay the same.” I teach in a suburban school district near Houston, TX and every few years, it seems the state decides we need to change the descriptions and requirements of the science courses.

Some of these changes are small, like the changes in verbs that require us to teach something to lesser or greater depth. Others are large, like the time they finally included the word 'moles' in the chemistry description, and half of the state when into a full-blown panic! But honestly, through all those changes we’re still required to teach science and a part of science — that is always included in some form or another is laboratory experiences.

As the paperwork requirements have expanded, along with the number of district and state-level tests, it seems that our time in the classroom has become more and more precious. Add to that the costs of materials and access to facilities, and you may find yourself wondering how you’re going to provide meaningful lab experiences for your students.

One solution that I’ve implemented over the past several years is to include Take Home Labs as part of my curriculum. My hope is to share with you some background behind my ideas, provide some suggestions and active links for several take home labs that are ready to use (for both Chemistry 1 and AP Chemistry), and try to alleviate some of your trepidation about incorporating this idea into your curriculum.

Multiple benefits

In addition to the obvious curricular focus that can be addressed, there are several great aspects about take home labs, including parent and family involvement, the increased relevance reinforced by the use of “real” materials, and the opportunity for students to experience science as something that happens everywhere, not just in the science classroom.

In our Pre-AP Chemistry classes, most of our take home labs include getting a parent or guardian’s signature as a graded component. We let the parents know about these during open house at the beginning of the year and encourage them to not only sign the student papers, but to also ask their students questions about their experiments and encourage them to allow siblings to participate. Additionally, because the labs are done at home, by their very nature they make use of readily available household and/or grocery store supplies, allowing students to see science happening with familiar materials and in familiar surroundings.

One of the greatest things about using take home labs is that you have a lot of flexibility as far as how you use them. I’ve used them to encourage students to explore and discover topics, to reinforce learning from my classroom or earlier learning, and as optional extra credit activities for students looking for ways to improve their grades.

A couple of labs that I’ve used for exploring and discovering are Ionic vs. Covalent Compounds and Abe Goes Swimming. In the Ionic vs. Covalent lab, students compare small samples of salt and sugar in terms of appearance, response to heating, and finally the elemental make-up (metal with non-metal vs. all non-metals). They create their own data tables, record observations, and answer questions including an extension piece.

In the Abe Goes Swimming activity, students compare the surface tensions of water and rubbing alcohol by “stacking” drops of the liquids on a clean penny. They create data tables, prepare graphs (Figure 1) and drawings for comparison, and choose their own extension piece from a list. The surface tension experiment can then be discussed in class, along with a lesson on intermolecular forces and their effects on the behavior of materials.

To refresh prior learning, I have used take home labs that emphasize the elements that make for a valid experiment, such as Magic Milk, and labs that review density, such as Can It Float? Magic Milk provides the students with an opportunity to make observations and then choose a variable (either heat or fat content) to manipulate and perform the experiment under the new parameters to see how that variable affects the results. In Can it Float? the students compare the densities of various materials to each other and to a standard of water. In our district, density is taught in junior high, but is still considered to be an intensive property for identifying materials that can be tested in chemistry. We find that students are coming in with a better understanding of density than they once did, but their grasp of the concept can still use refinement, so a take home lab is a way to reinforce the concept as a supplement to an in-class refresher.

From an AP standpoint, I have also created a few take home labs as optional extra test credit to help students who are not good test takers from the ‘paper and pen’ perspective, but are still willing to challenge themselves academically. I try to design these labs so that they offer experimental design and a little bit of research on new material, such as the Aspirin Tablets Lab, or a summary review of recent material like the Carbonate Identification Lab.

In the Aspirin Lab, students design an experiment to test the time and completeness of dissolution of various types of aspirin in different pH environments, while the Carbonate Identification Lab requires students to use gas laws and stoichiometry, along with some balloons and simple measuring tools, to identify a metal carbonate from a short list of possibilities.

The final category of take home labs would be those designed for extra credit. Extra credit labs are generally assigned as optional and proactive — i.e., they are due before the test to which they will be credited. One such lab is Little Miss Muffet (Figure 2) where the students make homemade glue from milk and compare it to commercial glue. In a lab like this, we might choose to emphasize new terminology (such as coagulation) that isn’t traditionally required by the state and try to add a review of some required concept (like neutralization) as a part of the questions that accompany the lab.

Figure 2. Arts & craft sample from the Miss Muffet lab.
Credit: A. Modic

Getting inspired

As you’ve been reading about these labs, I’m sure a few questions have come to mind, such as: How do you grade them? What if students can’t afford them? What about safety? Where do you get the ideas?

Let’s start with grading. Traditionally, we grade the take home labs by focusing on data tables and observations, answers to the questions, and having a parent/guardian signature. Labs are 30% of the grade in our school and we count take home labs as a one-time lab grade, whereas the formal labs done in the lab books count twice.

Most of our students can afford the materials and indeed, already have them at home; however, in some cases we will provide materials or let students come in before or after school to do the lab in our classrooms if that is easier for them. For the extra credit labs, I’ve had students bring their left-over materials for use by others who can’t afford to buy new materials!

As for safety, the students have signed a safety contract that includes a ban on unauthorized experiments, and we review the lab-specific safety with them before we send them home to complete the labs. Additionally, the parents have been notified earlier in the year about the take home experiences and that these experiences will require their signature (and hopefully a bit of participation). Certainly, people will have different comfort levels with an assignment like this and I think that you should choose what makes you comfortable, be it reminders to students and parents like I use, or having extra goggles for students to borrow. Some teachers do goggle dying at the beginning of the year, and this can be a great way to encourage kids to use them beyond the classroom.

Lastly, as to where I get the ideas, I look on the internet, go to conferences, and look in books — all with an eye for what could be done at home with a little (or quite a bit of) modification. I tend to look for topics that I feel can be experienced at home in such a way that it’s both interesting to the students and helpful to my curriculum.

As you can see, there are many possibilities for implementing take home labs into a chemistry curriculum, and they can be used in a variety of ways. In December I hosted an AACT webinar on take home labs and, in addition to the examples provided in this piece, there are more links to labs in the archive of that webinar. I encourage you to give it a try — especially if you’re feeling cramped for time or are looking for ways to make chemistry more relevant in your students’ lives. Science is all around us, and we should be encouraging our students to look for chemistry in the real world. Take home labs are one way to afford them this opportunity, and to let their parents see them doing science!