A: A great science investigation uses questions, activities, experiences, and examples to help students develop a concept, deepen their understanding, and apply the concept to new situations. A great lesson starts with some exploration of some phenomenon—perhaps a discrepant event, a toy that does unexpected or interesting things, or an attention-grabbing demonstration. This exploration can occur at the student’s own pace and with little guidance. Students often become highly motivated when they are permitted to do hands-on explorations before the concept is introduced.

Having piqued their curiosity, students are now ready to start learning and understanding what they observed. Discussing with one another in groups, some students might start to figure things out or at least have some ideas or hypotheses, which are tentative explanations. Students can learn to use and understand various science practices, such as observing, collecting data, categorizing, ordering, comparing, inferring, relating, communicating, and applying. They might then carry out another, more structured exploration allowing them to reexamine the same objects and phenomena more systematically.

We can then guide them to a more complete understanding. We’ll use scientific vocabulary to introduce the concept related to students’ observations. Note: Asking students to memorize definitions of terms is not science and does not result in long-term learning. What works better? Use a term in context, reminding students of the meaning the first few times you use the term. (After all, hearing words used in context is how we all learned to speak, right?)

Together, the teacher and students organize the observations and experiences, and the resulting patterns often match the targeted concept of the lesson. During discussion, the teacher and students compare how the newly introduced concept relates to students’ preconceptions. We can further explain the concept by using stories, pictures, video, and other materials.

After students receive the explanation, many teachers will conclude the lesson and move on to the next topic. But that shouldn’t be the end of the lesson. If we really want to create long-term learning—and be able to assess that learning—then we should give students opportunities, especially through the use of hands-on activities, to apply the concepts to other situations. These additional activities will often serve an additional purpose as being the initial activity in the exploration phase of a new, closely related concept that will be developed in the next lesson. In our quest to get students to appreciate the fascinating adventure that science can be, it is gratifying to know that the hands-on activities in the exploration and application phases can serve to motivate students as they encounter puzzles that arouse their curiosity.

Encourage Higher-Level Thinking

The research tells us that, to spark high-level thinking, teachers should ask questions that require some mental processing on the part of the student, rather than asking questions that only require a student to recall something from memory. Here are some questioning strategies that elicit higher-level thinking from students:

• Ask open-ended questions, such as, “Why do you suppose…?” or “What can you conclude from the evidence?”
• Ask students to state an idea or provide an explanation in their own words.
• Involve students in observing and describing an event or object by asking questions such as, “What do you notice here?” “Tell me about this,” and “What do you see?”
• Ask students to compare two or more objects, statements, illustrations, or demonstrations, and to identify similarities or differences between them. While identifying similarities, students will begin to recognize patterns that can lead to better understanding of a concept or generalization.

An Example Investigation

Students can learn a lot by trying to solve a practical problem. One way that this investigation is made more student-friendly is by the use of animal crackers. The idea is that an animal (cracker) needs to get to the other side of a river. Students can give their animal a name; let’s say, “Robbie the Rhino” (Figure 1). Robbie needs a raft in order to get over to the other side. Robbie needs to stay dry, otherwise, being an animal cracker, Robbie would get soaked and break up into pieces. The students’ job is, using the available materials, to make a raft that will float across a basin of water (Figure 2) with Robbie staying dry in the raft. Possible materials include craft sticks, aluminum foil, glue, tape, rubber bands, newspaper, toothpicks, plastic bags, cotton balls, etc. This activity involves both science and engineering.

Working in groups, students should discuss what materials would work best. If they need guidance, ask questions like, “What characteristics should the raft materials have?” One possible answer is that the materials must be waterproof. If a student mentions that, you can ask, “What does waterproof mean? How will you know if the raft is waterproof?” The idea is to get students to think about some tests they could perform with the materials prior to constructing a raft out of them.

Students might also realize that they need materials that will float. Here it would be useful for the students to understand buoyancy. I discussed buoyancy a bit in a previous Science 101 column (see Online Resources). Another useful concept is density. The key idea is that if the density of an object is greater than the density of water, then it will sink in water. If the density of an object is less than that of water, the object will float. Low-density objects don’t have much mass for their size. An example would be an air-filled balloon, which can easily be seen to float. A high-density object has a lot of mass and is heavy for its size, such as a coin or a rock, which will be seen to sink in water (Figure 3). Even without knowing any of that, students can experiment and discover that it’s the low-density materials (i.e., the ones that feel rather light for their size, that will float).

Matt Bobrowsky is the lead author of the NSTA Press book series, Phenomenon-Based Learning: Using Physical Science Gadgets & Gizmos. You can let him know if there’s a science concept that you would like to hear more about. Contact him at DrMatt@msb-science.com