1. What are things made of and how can we explain their properties?

Existence of matter anddiversity of materialkinds.

Objects are made of specific materials.

There are different kinds of materials.

The same kind of object can be made of different materials.

1. Objects^bare constituted of matter, whichexists as many differentmaterial kinds. Objectshave properties thatcan be measured anddepend on the amount ofmatter and on thematerial kinds they aremade of.

Objects have propertiesthat can be measuredand explained. Threeimportant propertiesare mass, weight, andvolume.

Objects have certain properties—weight, length, area, and volume—that can be described, compared and measured. (Only preliminary exploration and construction of volume measurement at this time.)

Objects are made of matter that takes up space and has weight.

Solids, liquids, and air are forms of matter and share these general properties.

There can be invisible pieces of matter (too small to see).

There are many different kinds of materials.

Matter has mass, volume, and weight (in a gravitational field), and exists in three general phases, solids, liquids, and gas.

Materials can be elements, compounds, or mixtures.

1AM. All matter is made of a limitednumber of different kinds of atoms,which are commonly bonded togetherin molecules and networks. Each atomtakes up space, has mass, and is inconstant motion.

Weight is an additive property of objects that can be measured (e.g., the weight of an object is the sum of the weight of its parts).

Volume is an additive property of an object that can be measured.

The weight of an object is a function of its volume and the material it is made of.

Mass is a measure of amount of matter and is constant across location; weight is a force, proportional to mass and varies with gravitational field.

Solids, liquids, and gases have different properties.

1AM. The mass and weight of an object isexplained by the masses and weightsof its atoms. The different motions andinteractions of atoms in solids, liquids,and gases help explain their differentproperties.

Materials have characteristic properties independent of size of sample (extends knowledge to include boiling/freezing points and to elaborate on density).

2. What changes and what stays the same when things are transformed?

Mass and weight areconserved across abroad range oftransformations.

There are some transformations (e.g., reshaping, breaking into pieces) where the amount of stuff and weight is conserved despite changes in perceptual appearance.

2. Matter can be transformed, but not createdor destroyed, throughphysical and chemicalprocesses.

Matter continues to exist when broken into pieces too tiny to be visible.

Amount of matter and weight are conserved across a broader range of transformations (e.g., melting, freezing, and dissolving).

Mass and weight (but not volume) are conserved across chemical changes, dissolving, phase change, and thermal expansion.

2AM: Mass and weight are conservedin physical and chemical changesbecause atoms are neither creatednor destroyed.

Materials can be changed from solid to liquid (and vice versa) by heating (or cooling) but are still the same kind of material.

Combining two or more materials can produce a product with properties different from those of the initial materials.

Some transformations involve chemical change (e.g., burning, rusting) in which new substances, as indicated by their different properties, are created.

In other changes (e.g., phase change, thermal expansion) materials may change appearance but the substances in them stay the same.

2AM: In chemical changes new substances are formed as atoms arerearranged into new molecules. Theatoms themselves remain intact.

3. How do we know?

Good measurementsprovide more reliableand useful informationabout object properties than commonsense impressions.

Measurement involves comparison.

Good measurements use iterations of a fixed unit (including fractional parts of that unit) to cover the measured space completely (no gaps).

Measurements are more reliable than commonsense impressions.

3. We can learn aboutthe world throughmeasurement, modeling,and argument.

Modeling is concernedwith capturing keyrelations among ideasrather than surfaceappearance.

Some properties of objects can be analyzed as the sum of component units. (Students are involved with the implicit modeling of extensive quantities through the creation of measures.)

Arguments use reasoning to connect ideasand data.

Ideas can be evaluated through observation and measurement.

Although measurements are more reliable than commonsense impressions, measurements can be more or less precise and there is always some measurement error.

Instruments, such as microscopes, can extend our ability to observe and measure.

Our senses respond to combinations of physical properties, rather than isolated ones. For this reason, they are not good measures of those physical properties.

Sources of measurement error can be examined and quantified.

We can learn about the properties of things through indirect measurement (e.g., water displacement) as well as using powerful tools (microscopes).

3AM. Atoms are too small to see directlywith commonly available tools.

Graphs, visual models, simple algebraic formulas, or quantitative verbal statements can be used to represent inter-relations among variables and to make predictions about one variable from knowledge of others.

Models can propose unseen entities to explain a pattern of data.

3AM: The properties of and changes inatoms and molecules have to bedistinguished from the macroscopicproperties and phenomena for whichthey account.

Good arguments involve getting data that help distinguish between competing explanations.