# Lesson 6: How Do We Interpret and Use Our Data?

This document will provide you with information on prep time needed, a list of supplies, and total lesson time for this particular lesson.

Students can use whatever means they are comfortable with to produce these graphs. Spreadsheet software of any type will do the job, as would graph paper and pencil. (We recommend a platform like Google Spreadsheets that allows students to easily share their results with one another.)

Finally,
students can calculate median response concentrations directly from a
spreadsheet’s formula for estimate of fit, or merely make a visual
estimation by interpolation directly from their graphs. Mistakenly, using a linear scale
(rather than logarithmic) will distort the curve somewhat, but not
unrecognizably. However, it will make interpolating GFC_{50 }more difficult.

Again, students should
recognize the
critical importance of **collecting all of their analyses and conclusions
into their notebooks,** including, but not limited to, their dose/response
curves, their estimates of median response dose/concentration, and the
like.

Students have now entered into their notebooks all of their observations and their analysis and interpretation of results, including producing dose/response curves for each of the biological responses they observed and estimating median response concentrations for those responses. They will next share their conclusions with the whole class.

The following
questions are likely to come up during this discussion, and might serve
as a useful guide:

One way to propel the
discussion to the higher levels of the next two discussion questions—from a consideration of the results of these particular
experiments to **a discussion of the appropriate next experiment**
and a higher-order **examination of the
experimental system itself**—might be with prompts such as the
following:

In most cases
(including this one), experiments in laboratory course classroom settings are necessarily
self-contained. In contrast, in research settings, each experiment is
just one step in an overarching research program occupying the time and
expertise of a whole team of scientists. Even more importantly, **the
goals of the
research program are not fixed, but depend directly on the results
generated by experiments**. Thus the process of actual research is recursive and
explicitly, deliberately, self-referential.

These insights are
difficult to demonstrate in the context of a laboratory course, and are
almost always outside of the direct experience of students. However, one
way to provide students with a glimpse into this process is to exploit the
intellectual momentum students obtain at key times, such as now when
they have just completed their interpretation of the results of an
experiment of their own design.

In fact, the typical behavior
through which
working scientists experience this process is that they habitually ask
themselves, just as soon as they draw conclusions from the results of
one experiment, **“What
is the next experiment?”**

Often the “next experiment” is two or three or five next experiments that might take place in parallel or in sequence. In some cases, the next experiment(s) will be variations on the previous one, each perhaps varying one experimental parameter or condition. In other cases, the next experiment(s) might call for an entirely different experimental system.

Students should
consider in their groups, and then report back to the whole class, their
answers to the question **“What is the next experiment?”**

Review the experimental system briefly; students are now intimately familiar with it: petri dishes, NaCl dilutions, one type of garden seed, and a 3-7-day incubation period.

During lesson 2, when students designed their experiments, they discussed the shortcomings (and advantages) of this system. Do they have any further criticisms based on their experience with it? What suggestions do they have for changing or extending this experimental system, and for what goals?