Lesson
/ Misconceptions
Stated in Teacher Guide / How Misconceptions are Addressed in Module Lessons / Teachers’ Notes
1 / o  Students may incorrectly believe that air is not a gas. They often associate the term “gas” with the gas used for cooking or with gasoline (TG pg.4). / o  “What is Matter” (SG pgs. 8-9) introduces the idea that air is made of a mixture of gases.
o  Students may incorrectly think that air and some gases are not forms of matter because they are invisible and their mass is not obvious (TG pg. 4). / o  “What is Matter” (SG pgs. 8-9) briefly states that air is made of gases that are a type of matter.
o  “Where Did Matter Come From?” (SG pg. 10-12) states that as gases cooled and condensed, “structures” that make up the universe were formed.
o  Lesson 4, Getting Started (SG pgs. 30-32) demonstrates that air has volume. Discuss their ideas (to Getting Started 5, SG pg. 32) and emphasize that both experiments show that what is often considered empty space does, in fact, contain something (in this case air) (TG pg. 42).
o  Lesson 25: students will hear a hiss when they release the carbon dioxide gas from the sealed bottle and a subsequent decrease in mass when they let the gas escape.
o  Students may incorrectly think that all liquids are water or contain water (TG pg. 4).
o  This misconception is listed again in Lesson 16. (TG pg. 173) / o  This misconception is not addressed in Lesson 1.
o  Lesson 3, Inquiry 3.1 (SG pgs. 26-27), students find the density of liquids other than water. They see that water doesn’t mix with these other liquids and that they have densities unique from water.
o  Lesson 16, Getting Started – students brainstorm liquids that do not contain water. Use the chart on page 175 of the TG to help guide this brainstorm.
o  In Lesson 16, students use solvents other than water to remove stains.
o  Students may incorrectly think that solids are nonmalleable. They may also have problems classifying plastic or flexible materials as solids (TG pg. 4). / o  Not addressed in lesson 1.
2 / o  Students incorrectly think that mass alone is the determining factor in floating and sinking; that is, heavy objects sink, and light objects float (TG pg. 17). / o  Lesson 3, Getting Started (SG pg. 25) will address this concept. The white plastic block will float, but the clear plastic block will sink. The clear plastic block has less mass than the white plastic block, yet it sinks.
o  Students incorrectly think that because mass and volume are both used to measure “quantities,” the terms are interchangeable (TG pg. 17). / o  “What is Matter” (SG pg. 8-9) defines volume and mass.
o  “Useful Calculations” (SG pg. 16) introduces the different method and tools used to measure both volume and mass.
o  When conducting Inquiry 2.1 (SG pgs. 16-17) be aware that the graduated cylinder is used to measure the volume of water, AND to hold the correct volume of water on the balance when measuring the mass. Students may struggle with seeing the difference between mass and volume when the cylinder is used for both measurements.
o  Discuss Reflecting Question 1A, 1B (SG pg. 20).
o  Students incorrectly assume that mass is affected by changes in shape (TG pg. 17). / o  Revisit Inquiry 1.7 (SG pg. 7) and measure mass of the pan squashed and not squashed. Or, students could use a piece of clay to discover the constant mass with shape change.
o  Students incorrectly believe that density and weight are the same (TG pg. 17). / o  Inquiries 2.2 and 2.3 (SG pgs. 18-19) further develops this concept as the students find some objects are heavier but less dense than others.
o  Students incorrectly believe that mass and weight are the same (TG pg. 17). / o  “Mass or Weight” (SG pg. 21) explains the difference quite well.
3 / o  Students may incorrectly think that all objects that float are hollow or contain air (TG pg. 28) / o  The use of liquids in place of solid objects (Lesson 3, Inquiry 3.1 SG pgs. 26-27) helps students understand that air is not always involved in floating (TG pg. 28).
o  This misconception can be perpetuated by Lesson 3, Inquiry 3.1 (SG pgs. 26-27). Be aware that in this lesson, students compare a hollow nylon spacer, that floats on the corn syrup but sinks in water, to a solid copper cylinder, which sinks in all three liquids. Emphasize that the spacer sinks in water and oil.
o  Point out that the solid wax and white plastic blocks both floated in Lesson 3, Getting Started (SG pg. 25).
o  Students may incorrectly think that density indicates thickness (for example, the density of a forest) or viscosity (for example, the thickness of paint); they often transfer these meanings to its scientific meaning (TG pg. 28). / o  Oil has a higher viscosity than water, however it floats on water. This could be emphasized in Lesson 3, Inquiry 3.1 (SG pgs. 26-27).
o  Students may incorrectly consider viscous liquids to be denser than thin liquids even though their own observations (such as seeing cream floating on coffee) contradicts this idea (TG pg. 28). / o  Through measurement and observation of density columns (Lesson 3, Inquiry 3.1 SG pgs. 26-27), students can see that viscosity and density are not related. The corn syrup and vegetable oil are more viscous than water, but the oil is less dense and the syrup is more dense than water (TG pg. 28).
4 / o  Students may incorrectly associate the term “gas” with fuel gases such as natural gas or gasoline (TG pg. 40). / o  “Deadly Density,” (SG pg. 34) describes chlorine as a greenish yellow gas.
o  “Air Heads,” (SG pg. 35-37) explains that air is a mixture of gases. The pie chart at the end of the reading (SG pg. 37) is a good graphic to go over with students.
o  Students may incorrectly consider air to have “negative mass” or “negative weight” because it is involved in floating (TG pg. 40). / o  Inquiry 4.1, Procedure Step 3 (SG pg. 33) should show students that air has mass.
o  Students may incorrectly think that objects that float in air defy gravity (TG pg. 40). / o  Review Inquiry 4.1, Reflecting Question 3 (SG pg. 33) to address this misconception. Discuss the density of air (that they just calculated) with the relative density of something floating in air.
o  Lesson 5, “Just a Load of Hot Air” (SG pgs. 46-47), discusses how a hot air balloon floats in air.
o  Students may incorrectly consider air pressure and gas pressure to be the same as density (TG pg. 40). (Many students who have been exposed to the concept of air pressure in the context of meteorology may use the term without understanding that it relates to force per unit area. Air pressure is measured in newtons per square meter, or pascals; This concept is very different from density which is the measure of mass per unit volume. However, there is a relationship between pressure and density. A gas at high pressure is denser than a gas at low pressure because particles of gas at high pressures are closer together.) (TG pg. 40) / o  Not addressed in this unit
o  The following is not listed as a misconception, however, when students use hard-walled bottles, it is not obvious that air is removed from the bottles when pumped. Students may struggle to see that the air is being removed from the bottle. / o  Students can use a soft-walled pop bottle instead of the nalgene bottles. This allows them to actually see the air leave the bottle. The method, however, makes it harder to measure the mass of the air. However, the air’s volume is already measure if using a 1 or 2 liter bottle. In addition, a balloon neck is used to seal around the washer and bottle.
5 / o  Students may incorrectly interchange the terms “heat” and “temperature,” thinking that temperature is a measure of the heat of an object. (TG pg. 50) / o  Lesson 7, Getting Started (SG pg. 65), is another opportunity to address students’ confusion between heat and temperature (TG pg. 82).
o  A pullout lesson would help students learn working definitions of heat and temperature.
o  Students may incorrectly think that thermometers measure heat; therefore, they may believe that heat is measure in degrees Celsius (rather than joules). (Thermometers measure temperature, which is the average kinetic energy of particles within a body.) (TG pg. 50) / o  “Measuring Temperature by Degrees” (SG pgs. 44-45) describes the Kelvin scale which sets zero degrees as the temperature at which matter contains no heat energy. Considerable discussion on this reading is necessary for students to understand the text and address their misconceptions.
o  Students may incorrectly think that the term “heat” refers to objects that are hot compared with the reference point of body temperature. (Heat actually refers to the transfer of energy from one body to another.) (TG pg. 50) / o  A pullout lesson is necessary here as this unit doesn’t address the definition of heat versus temperature.
o  Students may incorrectly think that heat is a substance with fluidlike properties that flows from one place to another. (TG pg. 51) / o  A pullout lesson is necessary here on convection, radiation, and conduction.
o  Students may incorrectly believe that “cold” can move into an object. For example, they may assume that “cold” from the ice water moves into their thermometers, pushing the liquid in the thermometer down. (In fact, heat only moves from “hot” to “cold.”) (TG pg. 51) / o  “The Trans-Alaska Pipeline: Meeting Nature’s Challenges” (SG pgs. 52-55) describes the problem of heat from the oil being moved causing the permafrost to melt. Emphasize that the scientists designing the pipeline were NOT worried that the cold from the permafrost would move into the oil and affect it in any way.
o  In the reading “Density Creates Currents,” (SG pgs. 48-51) this misconception could be supported as the diagrams show cool air moving. A thorough discussion of this reading is necessary.
o  Students may incorrectly think that the liquid in a thermometer goes up the tube because hot substances – such as hot air in a balloon – rise. (TG pg. 51) / o  Inverting the thermometer while reading a temperature may dispel this misconception. (TG pg. 51)
o  Lesson 5, Inquiry 5.1 Procedure Step 7 (SG pg. 41) asks what happens to the volume of water in the thermometer as the temperature increases. Inquiry 5.3 Reflecting Question 1A (SG pg, 42) also asks how volume is affected by temperature. These are opportunities to address this misconception.
o  “Changing Temperature, Changing Density” (SG pg. 43) explains that volume increases with increasing temperatures.
6 / o  Students may incorrectly think that matter is destroyed during chemical reactions. (This misconception may arise because combustion is used as a common means of disposal.) (TG pg. 68) / o  Not addressed in this lesson
o  In Lesson 22, Inquiry 22.2 (SG pgs. 201-203) students observe oxygen “disappearing” or being “destroyed” when it reacts with the iron. However, the Reflecting Question 2 pushes students to consider what new substance formed as the two reactants combined. Directions for how to obtain the correct understanding of this are listed in the TG, pages 269-270, Reflections 2-4.
o  Students may incorrectly believe that reactants disappear. (In fact, invisible products in the form of gases are often produced. The relationship between reactants and products may not always be an obvious one. Students’ existing cognitive frameworks may allow for the “magical” disappearance of reactants and the unrelated appearance of new substances but may not allow for the formation of one new substance from another. (TG pg. 68)
o  This misconception is also listed for Lesson 25. / o  Lesson 6, Inquiry 6.1, Procedure Step 20 (SG pg. 59): Potassium Permanganate and Copper Carbonate give off gases when heated (oxygen and carbon dioxide respectively) (TG pg. 67). This is not evident to the students but can be brought up when discussing the lab in the discussion described in Reflecting Question 1 (SG pg. 60).
o  “Heating and Changing Matter” (SG pg. 60) explains that an invisible gas can be formed.
o  Students may incorrectly assume that the production of gases as products of a chemical reaction is a phase change. (TG pg. 68) / o  Inquiry 6.1, Reflecting Question 1 (SG pg. 60) describes a class discussion. In the TG (TG pg.73) this discussion should include the idea that heating a substance may result in the formation of new substances that have very different characteristic properties compared with the original substance. This begins to address this misconception.
o  In addition, Copper carbonate (TG pg. 67) may help to discuss this misconception. Carbon dioxide is produced – a gas many students are familiar with. The name alone indicates that it is a new substance. In addition, there is another substance still in the test tube- indicating that it isn’t simply a phase change or all of it would have turned to a gas.
o  Students may incorrectly classify a phase change as a chemical reaction (for example, students may think that ice and water are two different substances and refer to their different properties to support this idea.) (TG pg. 68) / o  The sulfur test tube would ideally be used to address this misconception as it turns to a liquid then resolidifies to a solid in the original form when below 90°C (TG pg. 67). However, the liquid is yellow/brown and stains the test tube. As a result, it is difficult to see the original yellow powder at the bottom of the tube. This lesson doesn’t do a great job at addressing this misconception.