Video-Enhanced Automatically-Graded Web-Based Pre-Lab Tutorials

screenshot of tutorial with text: Video Enhanced Web-Based Pre-Lab Tutorials

In the freshman Chemistry laboratory course at Nicholls State University, tutorials (administered as Moodle quizzes) are used as pre-lab assignments. The tutorials consist of logically sequenced background information interspersed with several questions (multiple choice, numeric, short answer types) to check for understanding and were developed using Moodle’s embedded-answers Cloze question format. The text and graphical information provide a sufficient basis to answer all the questions. However, YouTube videos are embedded for students who may need additional help. Usage data from Moodle and YouTube analytics provide a wealth of information that can be used to gain insight on the effectiveness of the tutorials. The tutorials could be easily adapted for flipped instruction in high school and college lecture courses.

Typical Laboratory Instruction 

The teaching of introductory Chemistry laboratory courses is very similar at most colleges. Experiments are scheduled after the pertinent topics are covered in the corresponding lecture class. To prepare students and help them understand the results of the experiment, they are required to complete a written pre-lab assignment before class. Class time typically involves a short pre-lab lecture where the instructor gives an overview of the experiment, demonstrates proper technique, and addresses safety issues. Students then perform the experiment and complete a post-lab report after leaving the laboratory.

There are challenges associated with the aforementioned typical scenario. For example, in cases where the laboratory and lecture classes are not integrated, students who have taken the corresponding lecture class in an earlier semester may not remember the topic well. Manual grading of written pre-lab assignments takes time and delays feedback to the student. Pre-lab assignments tend to be short, which makes mindless cheating (i.e., copying of answers) quite easy. This defeats the purpose of a pre-lab assignment. Sufficient time must be allotted to allow all students to complete the experiment. Thus, instructors cannot spend too much time away from actual lab work for pre-lab lecture or post-lab discussion without sacrificing the breadth of topics/skills covered in the course.

Redesigning the Pre-Lab Assignment

We have started using Moodle to fulfill the goal of pre-lab assignments. A learning management system with an electronic assessment system, such as Moodle, is a very useful tool for facilitating the delivery and grading of pre-lab assignments. Our strategy is to make the pre-lab assignment easy and engaging enough for students to consider doing it a worthwhile investment of their time and effort. It serves as an introduction to students who have not been exposed to the subject and a review for those who have. Obviously, since the activity is not proctored, it is impossible to prevent cheating. We, in fact, do encourage student collaborations but urge students to consider it as a learning opportunity. The assignments count for 5% of the overall grade and achieving a high score is relatively easy. We allow multiple attempts for each assignment before the deadline (set before class starts); only the attempt with the highest score is counted towards a student’s grade. A one-week extension is given to allow students to improve their score, but they must wait 3 days between attempts; before the original deadline, no waiting is required between consecutive attempts. The only feedback provided before the extended deadline is whether each answer is correct or incorrect; the correct answers are provided after the extended deadline. There is no time limit (other than the deadlines) for each attempt.

The design of the tutorials implements explanatory questioning, one of three general principles that underlie methods shown to produce positive effects on learning, based on a comprehensive review of cognitive and educational psychology research literature by Roediger and Pyc (2012). According to Roediger and Pyc, explanatory questioning “involves students monitoring their learning and describing, either aloud or silently (i.e., to themselves), some features of their learning” and “slows reading (relative to simply zipping through the text, as some students do).”1

Figure 1: Screenshot of a question from Molecular Structure tutorial.2 

There are numerous platforms for implementing online tutorials. We found the Moodle quizzing tool to be more than adequate and quite easy to use. It takes about as much time to create the Moodle tutorials as it does to manually grade stacks of papers. Revisions, for subsequent uses, require even less time. Figure 1 shows a cropped screenshot of one of the questions (using Moodle’s embedded-answers Cloze question format) that a student sees in the tutorial on molecular structure. A PDF printout of the entire 15-question tutorial (with 341 embedded answers) is available in the pdf: 


Figure 2: Screenshot of question shown in Figure 1 in Edit mode.2

Figure 2 shows how the question is encoded using Moodle’s WYSIWG editor. Boxed sections of Figure 2 illustrate how simple answer and multiple choice questions can be encoded. A PDF printout of the editing page shown in Figure 2 is available in the citations. The code {1:SA:%100%6~%100%six} means that a simple answer worth one point (1:SA) is expected and a response of “6”or “six” would be given full credit (%100%). The code {1:MC:%100%H and C~H and N~C and N} means that a multiple choice question worth one point (1:MC) will be shown as pull down menu with H and C, H and N, and C and N as choices; answer of H and C is given full credit. It is possible to specify full credit for more than one correct answer, as well as partial credit for other answers. Simple answers can be made case-sensitive by using SAC instead of SA, as in {1:SAC:%100%Na}; in this case, an answer of “NA” or “na” will be considered incorrect. Numeric answers can also be encoded. For example, {1:NM:%100%18.0:0.1} means that the expected answer is 18.0 with a tolerance of 0.1; an answer between 17.9 and 18.1 would be considered correct.

Figure 3: Screenshot of Question 2 of Measurements tutorial.3


A wealth of insights can be obtained from using Moodle and your own YouTube videos. Figure 3 shows a screenshot of Question 2 of the Measurements tutorial. We created the embedded short video (about 2 minutes long) and YouTube analytics for January 2018 are shown in Figure 4. A spike in views from Louisiana was observed during the week when the tutorial was assigned. A total of about 96 students were enrolled in four laboratory sections and 85 views, with an average 80% retention rate, were recorded during that time period. The retention rate is the percentage of the entire video that played when the video was accessed.

Figure 4: YouTube analytics for embedded video shown in figure 3

We have since found a wide variability in the viewership rates for embedded videos; a careful analysis should provide insight into the need for the videos. A low viewership could indicate that the students already know the material well or that the textual information given in the tutorial are clear and easy to understand and apply. A high viewership could indicate the need to improve the textual information, or that a video might be necessary to effectively convey the information. In the case of the videos in the Measurements tutorial, the high viewership rates for video embedded in Question 2 that the the physical rationale behind significant digits is a concept that are somewhat difficult for students. A video on counting significant digits, embedded in Question 1 of the tutorial, had a significantly lower viewership rate, presumably because teachers spend more class time on this in several science courses since high school. It is therefore likely that students have already mastered this information and thus felt little need to view this video.


Figure 5: Partial screenshots of student performance from Moodle (Molecular Structure Pre-Lab Assignment).

Figure 5 shows partial screenshots of student performance data from Moodle for the Molecular Structure pre-lab assignment. The tutorial consisted of 15 multi-answer questions, which cover Lewis Structures, VSEPR, and orbital hybridization. The maximum possible 341 points for the 15 questions is scaled down to a grade of 10. Only scores for the highest attempts are shown in the Figure; the mean grade was 8.13 but the median was significantly higher (9.33). In the corresponding laboratory activity, done early in the semester, students are assigned molecules for which they draw Lewis structures, create wireframe and computer models, and present their work to the class. The topic is covered toward the end of the pre-requisite lecture class, which most of the students completed in the previous semester. In this particular case, it appears that students who tried to complete the assignment in one sitting spent about 1-3 hours and that it is fairly easy to get a high score on the first try. Later attempts typically take less time as students simply need to reenter answers marked correct and focus on the ones they missed in the previous attempts. Most students completed at least one attempt the night before the deadline (February 6, 2009 at noon). The best performing students only needed one attempt. Only a few students tried to improve their grades with additional attempts during the one-week extension.

Broader Impacts

The tutorials can also be useful as pre-class assignments for flipped lecture courses. An important key to successfully flipping lecture courses is being able to hold students accountable for reading or watching pre-assigned materials. Complementing the tutorials with randomly-varied assessments to enhance flipped lecture courses will be the subject of another paper. Another broader impact is the ease with which these tutorials can be shared with a large number of like-minded teachers. Moodle is a widely-used open-source learning platform. Even if one’s institution does not use Moodle, free Moodle hosting services can be utilized. The author highly recommends, which provides free hosting (limited to 30 users) and relatively inexpensive upgrade options. A growing question bank, which includes the tutorials described here, is maintained by the author at Temporary user accounts can be set up upon request for a teacher interested in examining the tutorials as well as the randomly-varied assessments that utilize the question bank. The question banks are available (for free) from the author ( as XML files that can be imported into any Moodle course site. The author would be glad to conduct a webinar (one-on-one or to a group of teachers) in setting up a free course site on, as well as create a series of how-to videos for using Moodle.


Using Moodle-administered, video-enhanced tutorials is a very convenient and appears to be an effective way to achieve the goal of pre-lab assignments. For the apparent benefits, developing the tutorials is certainly well worth the investment in time and effort.


  1. Roediger HL III and Pyc MA (2012). Inexpensive techniques to improve education: Applying cognitive psychology to enhance educational practice. Journal of Applied Research in Memory and Cognition 1, 242-248.

  2. Information about how to interpret a Lewis structure is provided before the embedded video; see Figure 2. A PDF "printout" of the entire 15-question tutorial (with 381 embedded answers) is available in the pdf.
  3. Screenshot of Question 2 of Measurements tutorial. YouTube analytics for embedded video ( are shown in Figure 4.