Classroom Instruction that Works: Research-Based Strategies for Increasing Student Achievement by Robert J. Marzano, Debra J. Pickering, and Jane E. Pollock identifies 9 categories of instructional strategies that have been shown through research to be effective in the classroom. They base their conclusions on meta-analyses done by researchers at Mid-continent Research for Education and Learning. It is important to realize that there is much overlap in the strategies and the good techniques in one strategy are often used to advantage to enhance the learning effectiveness of other strategies. Below we list the strategies employed in this web activity. The strategies are listed in order of effectiveness as rated by the average effect size (achievement in standard deviation units).
Identifying Similarities and Differences: Your students can use the strategy of Indentifying Similarities and Differences by comparing the data for the aerosol and cloud samples. Both data sets follow the same mathematical behavior because the laser intensity measured by Zot reduces by the same factor as each cell is added, but the factor is different for aerosols and clouds. This is an important lesson: the same mathematical behavior may apply to a variety of different situations (thus unifying and organizing understanding) even though particular values may differ.
Summarizing and Notetaking: Students should take notes as they make their observations. An effective note taking structure is to use the left side for notes in text, perhaps an outline, and the right hand sides for drawings and other graphical aids that help organize and clarify their observations. Finally, a summary can be written along the bottom as the groundwork that holds the structure together (download an MSWord version of the note taking structure). This method of notetaking would be effective in this activity if students put all their observations together on the same sheet or group of sheets. For the most effective use of this technique, have students discuss and compare their notes and summaries.
Reinforcing Effort and Providing Recognition: Reinforce students positively as they explore and make progress on their observations and discussions and as they begin to understand and organize their data using the power of mathematics. Have the students present their data, analysis, predictions and further measurements so you and the class can recognize their good work. If some groups of students are capable of going on to the more advanced challenges involving algrebra, exponentials, and logarithms, have them make presentations to the rest of the class. The very best reinforcement and recognition comes from parents, teachers, and other students.
Homework and Practice: You should assign reading about lasers, aerosols, clouds, and the atmosphere as homework. Students should plot their data on graph paper and tabulate their ratios. When they are finished with the first challenge, assign as homework a brief paper summarizing their data, analysis, predictions and further measurements. Make a similar assignment for the second challenge. High achieving students could be assigned challenges 3, 4, and/or 5 (see Extensions).
Nonlinguistic Representations: This activity is replete with nonlinguistic representations such as graphics and animations. Students will learn more from nonlinguistic actions as they explore the laser lab. If the students try Challenge 5 and deconstruct the Squeak project to find out how it works and construct a fifth test cell using the graphical tiles, they will be working with nonlinguistic representations of ideas (programming commands) and mathematics (arithmetic). The natural integration of these representations enhances the learning experience.
Cooperative Learning: Setting up cooperative learning groups is the recommended way to maximize student learning in this activity. Five defining elements of cooperative learning are: positive interdependence, face-to-face promotive interaction, individual and group accountability, interpersonal and small group skills, and group processing. Reciprocal Teaching is a research-based strategy that can be used effectively with cooperative groups. The four phases are summarizing, questioning, clarifying, and predicting. If you assign groups to work on measuring the aerosol or cloud test cells, it is important for each student to observe and take data. Then through discussion the team members can compare, summarize, analyze, question, clarify and learn mathematics together.
Setting Objectives and Providing Feedback: Objectives that are set shouldn't be too narrowly focused or learners tend to miss too much related material. For this activity a good objective would be to understand mathematically how Zot's measured laser intensity changes as more test cells are added to the test area. For each new test cell added the laser intensity drops by the same factor. This mathematical behavior occurs commonly in nature and can be used to describe many other phenomena. Students could offer feedback to other students through discussions explaining their data and analysis. If you give your students a test on the activity, research shows that the optimal time is one day after exposure to the material. Feedback on exams or projects has been shown to enhance learning and the best form is an explanation as opposed to just being given the correct answer.
Generating and Testing Hypotheses: Both inductive (abstracting a principle from a set of specific observations) and deductive (using a principle to predict a specific result) reasoning can be used to advantage to promote learning. Deductive reasoning activities have been shown to be more effective, but it depends on the circumstance. The division into inductive and deductive is often blurred and the concepts are most valuable when considered as two extremes of reasoning. This activity offers an excellent opportunity for students to reason both inductively and deductively and compare the two processes. When students take their initial data for either the cloud test cells or aerosol test cells, you should encourage them to explore the data and look for patterns. They could start by plotting the data and observe that the intensity Zot measures goes down each time. You could guide them to take the ratios of successive observations for the first three cells and they will see that the ratios are all the same. Then they should be able to apply induction to propose the general principle that each cell will reduce the intensity by the same factor. To test their principle using deduction, they should predict what the intensity will be when four cells are present and see that it agreees with their measurement. As a further test, they could compare the ratio of intensity for three test cells to that when one test cell is present. Their principle would tell them that they would see that the intensity reduces by the square of the ratio. You can devise many other similar tests to solidify and check your students' understanding. It has also been shown valuable for students to explain their hypotheses and predictions, which they could do as homework or in class or both if time permits. Part of the assignment could be to compare the processes of induction and deduction.
Cues, Questions, and Advance Organizers: These strategies all take advantage of students' prior knowledge and are good ways to start a lesson. As you give cues and ask questions, keep in mind that higher-order questions are more effective and students are more interested in things they already know something about. For example, good starting questions would be "What happens to the light beam when you shine a flashlight into water or a long ways through air at night?", "What do you think will happen to the intensity of the laser beam as it passes through the aerosol and cloud test cells?" and "How could we use Norbert and Zot's laser system to measure the thickness of any aerosol or cloud?" Remember that it is important to wait after asking your questions to give the students time to collect their thoughts before they respond - you will have a much better discussion. Don't worry if they don't get the correct answers, those are hard questions. The important thing is that your students are challenged to think. Advance organizers are a way of giving your students a brief "heads up" before starting a topic - they aren't outlines or summaries. Research shows the most effective advanced organizers are expository. In this case a story involving Norbert and Zot developing a aerosol and cloud measuring system for their weather forecasting business would work well.
