When considering a challenging science concept, I recalled struggling with explaining the concept of floatation, or “sink or float”, when teaching kindergarten. Although exploring objects that sink and float in water is highly intriguing for young students, the reasoning behind which objects sink and float can get complicated and too abstract for a student at that age to fully understand. Why does a tiny popcorn kernel sink and a large watermelon float?
In the BC’s New Science Curriculum, density is not specifically addressed until grade six when students investigate heterogenous mixtures. In Suat Unal’s (2008) research, he recognizes that elementary students possess significant misconceptions relating to floatation as evidenced through other research by Biddulph and Osborne (1984) and Gürdal and Macaroglu (1997). This other research finds that “students offered many unrelated factors such as mass and weight” to explain floatation activity, and that even after sink and float investigations and learning of Archimedes had been completed, students “were unable to construct scientific understanding” about sink and float relations (p.135).
In preparing a T-GEM lesson, I wanted to include student investigation of objects that sink and float in water, as well as in other liquids, to help student understanding of the concept of density. Because of this specification, the Gizmos simulation that is included in the following lesson is ideal, whereas other simulations that I found online provide investigation solely with water. An image of the simulation follows:
T-GEM Lesson – Density – Grade 6 (BC Curriculum)
Teaching Strategies | Student Activity | |
Read Aloud – Chapter 5, “Archimedes and King Hiero’s Crown” from Archimedes and the Door of Science by Jeanne Bendick. | Class discussion narrating ideas presented through reading; teacher comments neutrally | |
GEM – Cycle 1 |
||
G – Generate | Instruct students to investigate selected object in a sink and float investigation using water in a container. Students are to record observations on a T-chart as well as represent observations on a paper chart template using cut and paste images of the selected objects. Ask students to make a prediction about the types of objects that sink vs. float. | With a partner, students test sink and float tendencies of selected objects in water and record on a T-chart; Students place cut out pictures of objects onto chart template; After recording data, student journal predictions about the types of objects that sink vs. float. |
E – Evaluate | Ask students to record anything that does not make sense about their observations and prediction – questions they may have or confusing patterns; Ask students to think of a way to conduct a sink and float investigation that could help clarify some of the observations and predictions that do not make sense. Prompt students with a change in variable – either the solid objects or the liquid. Teacher guides student through extension investigations using an alternate liquid. | Students discuss with partner and record observations and predictions that don’t makes sense; Share questions and confusing patterns with class and plan a new investigation with changing one variable. Watch teacher directed demonstration and participate in class discussion. |
M- Modify | Ask students to determine what changes they need to add to their T-chart and paper pictorial chart to accommodate the new information accessed from the teacher-led investigation | Student makes adjustments to representations of t-chart and paper pictorial chart by including results with variable change. |
T-GEM – Cycle 2 |
||
G- Generate | Direct students to Gizmos online simulations: https://www.explorelearning.com {Teacher needs to previously set up an account and select simulation to add to their “class”.}
Lead students to the the elementary level lesson under Physics called “Density” Provide a short explanation of the activity, sharing that instructions are provided in text within the simulation. Remind students to record on a new chart the weight (g) of the object when measured on the scale, the volume displacement (mL)of the object within the graduated cylinder, and the the ability of the object to sink and float in each of the available liquids (water, oil, gasoline, sea water and corn syrup). After all objects have been tested, journal a relation statement based on the acquired data. |
In partners, students use the Density simulation measuring weight and volume displacement of the following objects: ping pong ball, golf ball, toy soldier, apple, chess piece, penny, egg, rock, gold nugget, crown 1 and crown 2. Students will test the floatation of each object in five different liquids and record their observations. Students will analyze their data and make a relation statement in their journal. |
E-Evaluate | Teacher provides students with the equation for density:
Density = Mass/Volume Water = 1.00 g/mL Oil = 0.92 g/mL Gasoline = 0.70 g/mL Sea Water = 1.03 g/mL Syrup = 1.33 g/mL |
Students compare the density of the measured objects using the density equation and with the density of the liquids and evaluate their relation statement making changes as necessary. |
M-Modify | Ask students to design a pictorial representation (model) of the data. Students can choose to represent objects that sink, or float, or both. The model should include density measurements of both the liquids and objects. The model should include a comparison of two or more liquids. Recommend using a chart or graph format with pictorial representations of objects. | Students choose data to include in their model representation following criteria provided by teacher. |