Academic journal article The Science Teacher

Achieving Liftoff: Using Coherent Storylines to Explain Phenomena

Academic journal article The Science Teacher

Achieving Liftoff: Using Coherent Storylines to Explain Phenomena

Article excerpt

Sense-making has been described as working on and with ideas--both students' ideas and authoritative ideas in texts (Campbell, Schwarz, and Windschitl 2016)--to build coherent storylines, models, and/or explanations. In this article, we describe our process for developing storyline units to support students' making sense of and explaining a rocket launch.

Storylines

The storyline approach, which aligns with the Next Generation Science Standards (NGSS Lead States 2013; see box, p. 41), engages students in "figuring out" instead of "learning about." The storyline approach features three key dimensions:

* an anchoring phenomenon chosen to spark questions,

* investigations that allow students to figure out parts of the story, and

* a culminating performance expectation that puts the story together.

Coherence is emphasized in storylines as students build ideas over time (Reiser, Novak, and Fumagalli 2015).

The Chemical Reaction, Energy, and Force storyline

For this storyline's anchoring phenomenon, we chose a specific portion of a rocket launch and articulated our own explanation of it (Figure 1). We then constructed a storyline to guide the day-today activities of the unit (Figure 2, p. 38). Initially, we developed the storyline by predicting questions students might ask. Each predicted question was then used to identify potential experiences (e.g., investigations, demonstrations) that students could use to explain the anchoring phenomenon. Each question represents a row in the storyline (Figure 2), and each row concludes with students figuring out something related to the rocket launch. Each row also leads to another question in the next row.

Day 1: Students' initial explanations

To begin the unit, we showed students a video clip of the rocket launch (see "On the web") and asked them to share initial ideas about how a large rocket can be lifted off the ground. After whole-class discussion, students worked in groups of two or three to develop an initial model that explained their ideas about the rocket launch. Groups shared their models in another whole-class discussion, then we elicited questions about the phenomenon. Next, we took up one of the questions that emerged: "What is fuel?" (Figure 2, Row 1, p. 38).

FIGURE 1

Teacher explanation of the anchoring phenomenon (rocket launch).

At first, chemicals used during rocket liftoff are in a less-reactive (stable) state, as can be seen in gases flowing out without any noticeable reaction. These chemicals (the fuel), like all matter, inherently have energy related to forces of protons and electrons of neighboring atoms. The bond energy between atoms is one type of energy. In some cases, matter can change without any added energy other than that taken from the surrounding environment--for example, the chemical reaction of baking soda with vinegar. In other cases, additional energy is required to destabilize the reactants and allow them to change. Just before rocket liftoff, sparks are applied to the fuel to provide this energy (the "activation" energy).

In a reaction that releases energy, the difference between the energy of the products ([H.sub.2]O) and the energy of the reactants ([H.sub.2] and [O.sub.2]) results in excess energy being released into the environment [exothermic reaction]. At the particle level, it takes less energy to break the bonds in [H.sub.2] and [O.sub.2] molecules than that released when the new bonds in [H.sub.2]O molecules form. This energy is released into the environment as heat, light, and sound. Once the reaction starts, the sparks can be removed because some of the released energy causes more hydrogen and oxygen atoms to rearrange into water (similarly, once a fire starts, you don't have to continue adding outside energy [heat] to keep the flame going).

To make the rocket launch, the chemical reaction takes place in a reaction chamber outside the fuel tank, where the gases are released at a controlled rate (not too fast or too slow). …

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