Student Preconceptions of Sound
As we teach we find that students have beliefs about magnets and electricity that are not quite true. We call these misconceptions but it is more accurate to call them preconceptions. Learners often jump to incorrect conclusions. We find those jumps to be a natural part of the process of learning about science.
Some of the most common misconceptions, or preconceptions, regarding magnets and electricity are listed below.
1. Students can struggle with why magnets stick to one nail and not all nails. It is very difficult for a child to broaden his/her horizons on the perception that if one thing works then so should the rest of them. Looks can be deceiving. Just because the nails look very similar on the outside, doesn't mean they are the same on the inside. Magnets only stick to iron and steel. Nails are made of different materials for different jobs.
The unit asks students to make drawings of their circuits. It is very important that teachers encourage the use of science notebooks to allow students to diagram their learning and their misconceptions. If your students have not done a lot of diagramming, model what the drawing should look like.
Remind them to date the drawings. Have students compare new and old drawings so they can see how their beliefs have changed.
2. In the lighting of one bulb using one wire and one battery, some students will insist that they need two wires. In some sense, the pre-assessment sheet on Page 10 in the Investigations 2 Folio encourages this. Many students will come to the classroom with the notion that the current stops at the bulb. When students begin to construct other circuits with two bulbs and switches, teachers should continue to ask for drawings and have students refer to previous drawings to determine if they have a different model.
3. Students should understand that the side of a bulb needs to be part of a bulb circuit (one of the critical contact points) in order for the bulb to light. To help them focus on the details of the connections, display a second drawing that shows the wire touching the side of the bulb. Encourage a debate about which one will light. Use this as a formative assessment to key in to how students perceive circuits at this point in the unit.
4. Students think if they add more batteries the bulb will get even brighter. Every bulb used has a certain voltage, just as the batteries do. If you exceed the voltages of the bulb with an excess of power from too many batteries, the bulb will become overloaded with power and either burn out quickly or explode. It's comparable to a balloon with too much air: it can't handle more than its capacity.