Consistent and accurate manipulation of liquids is essential for many biology
experiments. Teaching these skills is challenging in the laboratory. I have
developed Training Tips, a homemade teaching tool to train students to use
micropipettes in the classroom and laboratory. Training Tips provide obvious
visual targets that enable inexperienced students to know immediately if they
are pipetting accurately.
Key Words: pipetting; undergraduate education; high school education; liquid
handling; training tool; biology.
Pipetting is the principle technique used by bench scientists to
move microliters of liquid accurately. The proper and consistent
execution of this technique is essential for numerous scientific disciplines (Guzman, 2001; White et al., 2014). In particular, molecular biology protocols rely upon precise ratios of reagents (Lessard,
2013; Matsumura, 2015). Small deviations from these precise ratios
can have a variety of detrimental consequences, all of which lead to
decreased productivity and efficiency.
Determining if you are pipetting small volumes correctly is
challenging to check by eye. For instance, 1 μl (microliter) looks
significantly different depending upon the shape or size of the tip
that is used, and even for experienced bench scientists, visually
assessing the difference between 800 μl and 850 μl is difficult.
Many pipette tips have gradations marked at significant volumes,
for example 20 μl and 100 μl. However, the broadness and transparency of these gradations render such markings only minimally
helpful as a training tool. Given these challenges, it is critical that
we develop tools to aid in teaching inexperienced scientists the
foundational skill of pipetting so they can focus on and are better
prepared to develop more advanced techniques critical to their scientific training.
To help teach students and inexperienced bench scientists to
use micropipettes, I have developed Training Tips, micropipette
tips that are clearly marked and labeled. The markings provide a
visual target for beginner bench scientists to use as a guide for
how far up the tip different volumes of liquid should reach. Students experience how depression and release of the plunger feels
when the mark is hit versus when it is not. This instant feedback
is helpful for novice bench scientists, and provides critical, individual feedback impractical for single instructors to give a large group.
Training Tips are homemade sets of marked pipette tips that guide
the trainee as they learn to use micropipettes. In our lab, we most
often pipette between 0.5 μl and 1000 μl, so I have developed three
sets of training tips used with either the P1000, P200/20, or P10
pipette. To craft Training Tips, pipette a volume of water into the
pipette tip and mark the meniscus with a black marker. Mark each
tip at only a single volume. Making the lines on Training Tips as
close to parallel with the base of the tip is important. Wrapping
tape slightly above and below the meniscus, coloring the exposed
region, and removing the tape can generate neater lines but
increases how long it takes to make each tip. On the P1000 tips,
1000 μl through 200 μl are marked at 50 μl intervals. For P200/
20 tips, from 200 μl to 20 μl are marked at 10 μl intervals. In addition, the P200/20 tips are also marked at 15, 10, 7.5, 5, 2, and 1 μl
For P10 tips, between 10 μl and 1 μl were marked at 1 μl intervals. Depending upon the training situation, more or fewer tips may
be appropriate. On one side and the top of each tip, I have labeled
what volume the mark designates (Figure 1B). The black marker
lines on Training Tips are easier to see than the clear gradations provided on standard tips. In addition, most standard tips provide only
one or two gradations, limiting the students’ ability to check their
accuracy. Training Tips are marked at finer gradations and at a single
The American Biology Teacher, Vol. 80, No. 7, pp. 536–539, ISSN 0002-7685, electronic ISSN 1938-4211. © 2018 National Association of Biology Teachers. All rights
reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Reprints and Permissions web page,
www.ucpress.edu/journals.php?p=reprints. DOI: https://doi.org/10.1525/abt.2018.80.7.536.
TIPS, TRICKS &
Training Tips: Tools to Teach
Pipetting in the Classroom and Lab
• DOUGLAS A. BERNSTEIN