Student Preconceptions
Describe tools used to determine student preconceptions:
1. Tool and place in unit: Page Keeley, Understanding Science Volume I
Physical Science Assessment Probes
These tools are designed to draw out the following preconceptions from students:
- Ice Cubes in a Bag – Conservation of Matter, Change in State, Physical Change, Closed Systems
- Lemonade – Conservation of Matter, Dissolving, Physical Change, Mass or
Weight
- Cookie Crumbs – Conservation of Matter, Mass or Weight, Physical Change
- Seedlings in a Jar – Conservation of Matter, Atoms or Molecules, Chemical
Change
- Is it Melting? – Dissolving, Change in State, Physical Change, Melting, Heat
Energy
- Is it Matter? – Atoms or Molecules, States of Matter, Mass or Weight
- Is it Made of Molecules? – Atoms or Molecules, Matter
- The Rusty Nails – Mass or Weight, Chemical Change
- The Mitten Problem – Heat Energy, Temperature
- Objects and Temperature – Heat Energy, Temperature
2. Tool and place in unit: Page Keeley, Understanding Science Volume
II Physical Science Assessment Probes
These tools are designed to draw out the following preconceptions from students:
- Comparing Cubes – Atoms or Molecules, Characteristic Properties, Density,
Mass
- Floating Logs – Characteristic Properties, Density, Floating and Sinking
- Floating High and Low – Buoyancy, Characteristic Properties, Floating and
Sinking, Density
- Solids and Holes – Characteristic Properties, Density, Floating and Sinking
- Turning the Dial – Boiling Point, Change in State, Characteristic Properties,
Heat Energy
- Boiling Time and Temperature – Boiling Point, Change in State, Characteristic
Properties
- Freezing Ice – Characteristic Properties, Freezing Point, Temperature
- What’s in the Bubbles? – Atoms or Molecules, Boiling Point, Change in State,
Heat Energy
- Chemical Bonds – Atoms or Molecules, Chemical Bonds
- Ice Cold Lemonade – Conduction, Energy Transfer, Heat Energy
- Mixing Water – Conduction, Energy Transfer, Heat Energy, Temperature
3. Tool and place in unit: Page Keeley, Understanding Science Volume
III Physical Science Assessment Probes
These tools are designed to draw out the following preconceptions from students:
- Pennies – Atoms, Properties of Matter
- Is It a Solid? – Liquids, Solids, Properties of Matter
- Thermometer – Kinetic Molecular Theory, Thermal Expansion, Thermometer
- Floating Balloon – Density, Gases, Kinetic Molecular Theory, Mass, Properties
of Matter
- Hot and Cold Balloons – Conservation of Matter, Gases, Kinetic Molecular Theory, Mass
4. Tool and place in unit: Page Keeley, Understanding Science Volume
IV Physical Science Assessment Probes
These tools are designed to draw out the following preconceptions from students:
- Sugar Water – Dissolving, Mixture, Physical Change
- Iron Bar – Atoms, Thermal Expansion
- Burning Paper – Chemical Change, Closed System, Conservation of Matter,
Combustion
- Nails in a Jar – Chemical Change, Closed System, Conservation of Matter,
Oxidation
- Salt Crystals – Atoms, Crystals
- Ice Water – Energy, Temperature, Phase Change, Phases of Matter, Transfer of
Energy
- Warming Water – Heat Energy, Temperature, Transfer of Energy
Part 1: Characteristic Properties of Matter
Lesson 1
Description of a student preconception:
1. Air is not a gas.
Students associate “gas” with gasoline or other fuel sources.
2. Air is not
matter because it is invisible.
3. All liquids are water or contain water.
4.
All solids are rigid.
Correct conception by the end of the unit:
1. Air is a gas because it does
not have a definite shape or volume and can flow.
2. Air is matter because it
has mass.
3. There are many types of liquids. Liquids have a definite volume,
but no definite shape and can flow.
4. Some solids can be shaped such as plastic
or clay.
Lesson 2
Description of a student preconception:
1. Objects float and sink
depending only on their mass.
2. Shape affects an object’s mass.
3. Density and
mass are the same as weight.
Correct conception by the end of the unit:
1. Floating and sinking depends on
the density of the object. Large, heavy objects can float if their density is
less than the density of the substance they are floating in.
2. Mass will only
change if some matter is removed from an object.
3. Weight of an object can vary
because it is determined by the force of gravity on the object, but mass and
density of an object are determined by the amount of matter in the object.
Lesson 3
Description of a student preconception:
1. Objects that float
contain air.
2. Density is the “thickness” of a substance. Example: “thick
forest” or “thick paint”.
Correct conception by the end of the unit:
1. Floating and sinking depends on
the density of the object. For example, some liquids can float on other liquids.
2. Thickness only tells the width of a sample, not how compact the matter in the
sample is.
Lesson 4
Description of a student preconception:
1. Air is not a gas.
Students associate “gas” with gasoline or other fuel sources.
2. Air has
negative mass because it floats.
3. Objects that float are not affected by
gravity.
Correct conception by the end of the unit:
1. Air is a gas because it does
not have a definite shape or volume and can flow.
2. Air has mass, but a very
low density.
3. Objects that float in air are less dense than air.
Lesson 5
Description of a student preconception:
1. Heat and temperature are
the same.
2. Thermometers measure heat.
3. Heat describes things that are hot.
4. Heat is a form of matter that can flow on its own.
5. Coldness can move from
one object to another.
6. Liquid moves up a thermometer because heat rises.
Correct conception by the end of the unit:
1. Heat is a form of energy. A
sample of a substance may contain a lot of heat energy, but still have a low
temperature (average amount of kinetic energy.)
2. Thermometers measure
temperature.
3. Heat energy can transfer from a warmer substance to a cooler
substance. Things feel “hot” because they are warmer than my body temperature.
4. Heat is a form of energy. Heat moves through solids by conduction.
5. An
object feels cold because heat energy is being transferred away from that
object. There is not such thing as “coldness” or “cold energy.”
6. Liquid moves
up a thermometer because the liquid is expanding (becoming less dense.)
Lesson 6
Description of a student preconception:
1. Matter is destroyed
during chemical reactions.
2. Some reactants disappear during chemical
reactions. Students may associate a decrease in size of a reactant with the
“destroying of matter.”
3. All gases produced during a chemical reaction went
through a phase change.
4. Phase changes are types of chemical reactions.
Correct conception by the end of the unit:
1. Matter is conserved in all
chemical reactions.
2. Reactants can change into invisible gases during chemical
reactions.
3. Some chemical reactions produce gaseous products which are new and
different substances than the original reactants.
4. Phase changes are physical,
not chemical, changes. In a phase change, the type of substance does not change.
Lesson 7
Description of a student preconception:
1. Loss of mass occurs when
matter changes state.
2. Melting and dissolving are the same.
3. Turning up the
heat during boiling increases the boiling point.
4. Water always boils at 100˚C.
5. Substances that boil are always hot.
6. Substances that melt are always hot.
7. Phase changes are chemical reactions.
8. The freezing point is lower than the
melting point of a substance.
Correct conception by the end of the unit:
1. Mass is conserved during all
phase changes.
2. Melting is a phase change from solid to liquid. Dissolving is
when a substance breaks up into tiny pieces and spreads throughout a solvent.
3.
Temperature remains constant during boiling. Boiling point is a characteristic
property of a substance.
4. The addition of impurities affects water’s boiling
point. Water’s boiling point is measured at standard temperature and pressure.
5. Boiling point of a substance is whatever temperature the substance turns from
a liquid into a gas. For example, oxygen is already a gas at room-temperature
and is not considered “hot.”
6. Melting point of a substance is whatever
temperature the substance turns from a solid to a liquid. For example, 10˚C
water feels very cold, but has already melted.
7. During a phase change, the
type of substance remains the same. For example, water ice, liquid water, and
water vapor are all water.
8. Freezing point and melting point are the same
temperature; they just describe the direction of heat energy transfer (heat
energy transferring into or out of the substance.)
Lesson 8
Description of a student preconception:
1. Mass and volume are the
same.
2. When substances melt, evaporate, or boil they lose mass.
3. When
substances freeze, they increase in mass.
Correct conception by the end of the unit:
1. Mass is the amount of matter in
an object and volume is the amount of space the object takes up.
2. Mass is
conserved during all phase changes.
3. Mass is conserved during all phase
changes.
Part 2: Mixtures and Solutions
Lesson 11
Description of a student preconception:
1. A pure substance is safe
to use or eat.
2. A pure substance is something without preservatives and
artificial sweeteners.
3. Pure means clean. Pure means clear.
4. Pure substances
are made only of one element.
5. The various components of a mixture are all
visible in the mixture.
6. Compounds are one type of mixture.
Correct conception by the end of the unit:
1. “Pure” means a substance is
composed of only one type of element or compound.
2. A pure substance is
composed of only one element or compound.
3. “Pure” only tells about the
composition of a substance.
4. Many pure substances are made of only one type of
compound.
5. Mixtures may contain dissolved substances that cannot be seen with
the naked eye.
6. Compounds are not classified as mixtures because the elements
are chemically bonded.
Lesson 12 and 13
Description of a student preconception:
1. When a substance
dissolves in water, it disappears.
2. When a substance dissolves in water, it
becomes water.
3. Dissolving is the same as melting.
4. Dissolved particles can
be filtered out of solution or will eventually settle to the bottom.
Correct conception by the end of the unit:
1. When substances dissolve, they
break apart into tiny pieces that are too small to see with the naked eye.
2.
Dissolved substances do not undergo a chemical change.
3. In dissolving, the
solvent must act on the solute to break it apart whereas melting only requires
the addition of heat energy.
4. Dissolved particles are too small to be filtered
and must be separated by evaporation of the solvent.
Lesson 14
Description of a student preconception:
1. Measurements of mass or
volume report the same property of a substance.
Correct conception by the end of the unit:
1. The same mass of a substance
can take up different volumes of space.
Lesson 15
Description of a student preconception:
1. Filters remove all added
substances from a solvent.
2. Filters will remove all color from water.
3.
Filters purify water.
Correct conception by the end of the unit:
1. Filters only remove insoluble
substances from a solvent.
2. Color in water is from dissolved pigments that are
soluble and too small to be removed by a filter.
3. “Pure” only tells about the
composition of a substance.
4. Filters only remove the insoluble components from
a water-based solution or mixture.
Lesson 16
Description of a student preconception:
1. All liquids contain
water.
2. One “stain remover” will remove all kinds of stains.
Correct conception by the end of the unit:
1. Liquid is a state of matter.
Substances have characteristic melting points at which they undergo a phase
change from solid to liquid. Example: water’s melting point is 0˚C, sodium
nitrate’s melting point is 306˚C.
2. Some substances dissolve in one solvent and
not in another.
Lesson 17
Description of a student preconception:
1. Chromatography separates
colors. (Example: green ink will become only yellow and blue.)
2. Chromatography
can only be used on colored substances.
Correct conception by the end of the unit:
1. Chromatography separates
solutes. (Example: green ink will become any combination of pigments that were
dissolved to create that dye.)
2. Chromatography can separate any solutes,
whether they are colored or not.
Lesson 18
Description of a student preconception:
1. Impurities cannot change
the characteristic properties of a substance.
2. All solder alloys have the same
properties.
Correct conception by the end of the unit:
1. Impurities often change the
characteristic properties of a substance. (Example: salt will increase the
boiling point of pure water.)
2. The properties of solder are determined by the
percentage of each substance that comprises the alloy.
Part 3: Compounds, Elements, and Chemical Reactions
Lesson 20
Description of a student preconception:
1. Compounds are mixtures
of elements.
2. Compounds are not pure substances.
Correct conception by the end of the unit:
1. Compound are made of elements
that have been chemically bonded.
2. Compounds are pure substances. Compounds
have their own characteristic properties.
Lesson 21
Description of a student preconception:
1. All metals are magnetic.
OR Only iron is magnetic.
2. Only metals can conduct electricity.
3. Graphite is
a metal because it can conduct electricity.
4. All elements are solids.
Correct conception by the end of the unit:
1. Magnetism is a characteristic
property of some metals.
2. Some non-metal substances can conduct electricity.
3. Graphite has properties of metals and non-metals.
4. Elements exist in nature
as solids, liquids, and gases.
Lesson 22
Description of a student preconception: See Lessons 6 & 21.
Correct conception by the end of the unit: See Lessons 6 & 21.
Lesson 23 and 24
Description of a student preconception:
1. Acids dissolve metals to
form solutions. It looks like the metal itself is becoming part of a solution.
2. All chemical reactions release heat. (Exothermic reactions.)
3. Corrosion
causes objects to break down.
4. Rust corrodes iron.
Correct conception by the end of the unit:
1. Acids can chemically react with
metals to form new substances that are soluble. The new and different substance
formed by the chemical reaction (ex. salt) dissolves in water so it can’t be
seen.
2. Some chemical reactions require heat as the catalyst. (Endothermic
reactions.)
3. Corrosion is a process, not the cause of the process. (An object
can be corroded by another substance.)
4. Rust is a product of corrosion. (Iron
and oxygen react to form rust – iron oxide.)
Lesson 25
Description of a student preconception:
1. Matter can get lighter
or matter can disappear during a chemical reaction.
2. Chemical reactions can
create new matter.
Correct conception by the end of the unit:
1. Matter cannot lose mass,
although it may change form and location. (Example: gaseous products.)
2. A new
form of matter may result from a new chemical combination of part of the
original reactants.