Perhaps the first assay we learned in science class was the starch test, where we dropped iodine on a substance, and if it turned “blue-black”, it indicated the presence of starch.

Now, as modern-day science teachers, we carry on the wisdom of generations of science teachers, and continue to avoid calling the positive result “black and blue”, as no science teacher wants students to associate bruises with white bread or potatoes.

The starch test has become such a common test, that I believe the term “starch test” should replace “litmus test” as the analogy cliché for social or political tests. (For example, Wikipedia states, “A litmus test is a question asked of a potential candidate for high office, the answer to which would determine whether the nominating official would choose to proceed with the appointment or nomination.”) How many non-science teachers even know what litmus is or what a litmus test is? Let’s start using analogies more people can relate to. [People would really start liken that (with an intended pun on the nature of litmus)!]

Today is the six-month anniversary of this blog. It seems such a short time ago, but alas, on June 20, 2008, my first blog was posted. This made me wonder, “How does one know if one is successful after just six short months?

To find the answer to this query, I did a search on blogs. I found no numerical metrics for success. Looking at the latest report from Google Analytics, I did see that more than 35 people per day have read this blog, and that this month alone, there were over 1,000 readers from 70 countries/territories.

The search for blogs about blogs (i.e. metablogs) yielded no numbers, which I viewed once again as evidence that collective wisdom can often be found in groups of people. The qualitative metric I did derive, however, from reading the advice of more experienced blog pundits was this: If a blogger enjoys writing about their interests, and some people are reading, then it should be considered successful. As far as this starch test is concerned, I judge this blog as a success, and I thank you for reading it.

But now on to science teaching and technology, which is the focus of this blog. In the living world, photosynthesis is one of the most important processes. Fortunately, Adaptive Curriculum has a free interactive activity that teachers and students (from all 70 countries/territories) can use to learn more about photosynthesis. In “Plants Needs for Photosynthesis” students conduct several investigations, where they can add or subtract water, light, carbon dioxide, and oxygen. The plant then does its thing (AKA: metabolism) for four hours.

After this, the starch test is performed to see if photosynthesis occurred. In the starch test, the leaves are boiled and then dipped into hot alcohol to remove the green chlorophyll. Next, the leaves are dipped into room temperature water. Finally, drops of iodine are placed upon the leaves. Through these discovery-based learning experiences, students are able to determine the conditions that are needed for photosynthesis to occur.  

Thank you to Adaptive Curriculum for giving us this free Flash-based activity, and for their support of this blog. And no matter what your starch test or litmus test for happiness may be, I wish you a happy holiday season.

Resources:

If you (or your students) don’t know what a litmus test is, here are some links:

Adaptive Curriculum’s “The Properties of Acids”

Adaptive Curriculum’s “The Properties of Bases”

Adler, Kris Lesson Plan: The pH scale. 

As a long-time advocate of hands-on science (Perspectives of Hands-On Science Teaching  Haury & Rillero, 1994), I believe that hands-on science with physical entities is an important part of science classrooms. As examples consider science experiments where students hold and manipulate physical things, such as spring balances, magnets, and earthworms. I believe virtual experiences are a compliment – not a replacement for— physical experiences and other forms of instruction.

There are of course situations where physical hands-on science experiences are not possible. Some science experiences may be too dangerous, too long, or too expensive and therefore virtual experiences can be a great way to provide the experience without the “too” problem. There are also some educational contexts where physical hands-on science can be problematic. For example, at an NSTA conference one of the teachers who was very excited about how Adaptive Curriculum worked in a prison for adolescents. She told me that it was against prison rules to allow any physical hands-on materials into the classroom. Thus she was very interested in virtual experiences. While most science teaching situations are not this extreme, it is, however, the norm, rather than the exception that a lack of funds, material, equipment, or preparation time limits the quality or the amount of hands-on experiences we provide.

Perhaps I had a misconception about virtual experiences. I just assumed the physical experiences would be better than the virtual experiences. But then I came across a research study published in a top science education journal entitled: “Hands on What? The Relative Effectiveness of Physical Versus Virtual Materials in an Engineering Design Project by Middle School Children” (Klahr, Triona, & Williams, 2007). According to the authors, “The purpose of this study was to determine the effects of putting learners’ hands on virtual rather than physical materials in a scientific discovery context.”

The study compared constructing physical and virtual mousetrap cars and the learning outcomes. Pretests were conducted on student knowledge and constructing an optimal distance car. Based upon pretest-posttest gains on the content exam students were either classified as “learners” or “non-learners.” In the physical group there were 14 learners and 14 non-learners. In the virtual group there were 16 learners and 12 non-learners. Although the physical group outperformed the virtual, this was not a statistically significant difference.

When it comes to the designing the Optimal Distance Car test, all groups designed cars that went farther from pre to post test. There were no significant differences between the groups. Of course, educational researchers don’t usually get too excited about finding “no statistically significant difference.” In this study, it is interesting, however, because it suggests that the learning may have been equivalent.

The authors of the study point out that the virtual experiences were far easier for the teachers because they didn’t have to gather and distribute materials and find special hall locations for the students to conduct their tests. The study also suggested efficiencies for the students. Half the students in each group had limited time to build their cars; half had a limit on the number of cars they could construct. When time was limited, virtual group tested more cars (average =20.1) than physical group (6.1), which was a statistically significant difference. When number of cars was restricted to six, virtual students did it in less time (6 minutes versus 20 minutes). Being able to do more in the same time or the same in less time, both with the same learning outcomes, does indeed help show the value of virtual experiences.

But in my opinion the value of virtual science experiences, is still as a complement to the physical experiences rather than as a replacement. I don’t know of studies that support this opinion but I suspect that most science educators would agree with this position. So for me, we should focus less on “Physical Versus Virtual Hands-On Science Experiments” but more on how virtual experiences can enhance overall science teaching and learning.

References:

Klahr, D., Triona, L.M., & Williams, C. (2007) “Hands on What? The Relative Effectiveness of Physical Versus Virtual Materials in an Engineering Design Project by Middle School Children,” Journal of Research in Science Teaching, 44(1), pp 183-203.

Haury, D.L., & Rillero, P. (1994). Perspectives of Hands-On Science Teaching. Columbus, OH: ERIC Clearinghouse for Science, Mathematics, and Environmental Education.