Though models are invaluable for science instruction of students with visual impairment, students should be taught that models are not usually a perfect representation. Models often have weaknesses that must be understood in order to best grasp the concepts taught.
After initial instruction on the structure of the atom using the Azer model and the science text for the class, the following activity will help students understand better the relative distance between the nucleus of an atom and the electron levels.
Explain to students that the model we are using (the Azer atom model) has both strengths and weaknesses. Tell students that this is the case for most models.
This activity will allow the students to determine one or more of the weaknesses of the model and to better understand the atom.
The only preparation necessary is to gather the materials.
Students may need to be taught to use the trundle wheel.
Each student will be provided with the Azer model prior to the walk and with the small marble as a model of the size of the nucleus prior to the walk. Tell students prior to the walk that most models have weaknesses and that their task is to decide what weakness (or weaknesses) this model has based on what we learn from the atom walk. How is the model different from what we learned about the structure of the atom ?
Given this model, if the nucleus were the size of a marble, the outer edge of the atom would be 100 meters away.
Divide the 100 meters by the number of students in the class and bring the marble for other students to hold as you walk. Discuss the nucleus and its size as you walk.
As students return from the walk, they will each write a paragraph independently describing how they think the model of the atom is different from the model of the atom that we just walked. Azer models should still be displayed for each student. Give students at least 5-10 minutes to think and write depending on the group.
Closure: Discuss the model and its deficiencies. Students should first of all describe the distance to the electrons compared with the model on the table. Ask the students if there are other differences based on this new model. The amount of space in an actual atom compared with the nucleus. Talk about how dense the nucleus is in relation to the rest of the atom.
End by discussing why this model had to be built in this manner (so that it would fit on the table).
We have discussed the model’s weaknesses. What are its strengths?
These may include that the protons and neutrons are correctly placed in the nucleus while the electrons are outside of the nucleus. The students may also indicate that this model differentiates between protons, neutrons, and electrons clearly with different shapes and colors.
If a longer or shorter walk is desired the size of the sphere (nucleus) and the length of the walk can be adjusted accordingly.
By Laura Hospitál
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