# physical properties

## That's the Way the Ball Bounces (or Is It?)

In this Activity, students investigate the physical properties of different balls that may look similar, but have very different rebound properties. Students also investigate how the rebound properties change when the balls are subjected to near freezing and near boiling temperatures. This Activity could be used at the beginning of the school year as an exercise in making observations.

## How Heavy Is a Balloon? Using the Ideal Gas Law

In this Activity, students explore buoyancy with helium-filled Mylar balloons. They use the ideal gas law to predict the mass of the balloon if it were empty, compare it to the actual mass of the empty balloon, and discuss experimental sources of error. This Activity demonstrates the ideal gas law and introduces students to the concept of buoyancy.

## Bowling for Density!

In this Activity, students predict whether a given bowling ball will float or sink in tap water. Students design a procedure to collect radius and weight measurements to calculate the density of their ball. They then test their prediction by placing the ball in a large container of water, which yields the surprising observation that some bowling balls do float.

## The Nature of Hydrogen Bonding

In this Activity, students build models of polarized water molecules using K’nex toy components and adhesive Velcro. Students investigate hydrogen bonding by shaking the models in various ways. They observe the resulting interactions and relate their observations to physical states of water and the difference between strong bonds and weak attractions.

## Popcorn: What's in the Bag?

In this Activity, students investigate microwave popcorn, the process of microwave-promoted popping, and the materials involved: water, vegetable oils, starch, and special packaging materials. This Activity supports discussion of thermal and electromagnetic energy, phase changes, intermolecular forces, patterns of solubility, and the structure of fats, oils and starches.

## Chemistry of Cement

In this Activity, students use a commercial cement mix to produce concrete. They investigate how changing key variables such as concentrations, curing temperatures, and the addition of various substances affects properties such as setting time, hardness, and plasticity.

## Whatever Floats (or Sinks) Your Can

In this Activity, students test whether cans of carbonated beverages sink or float in water and then determine whether caffeine content, soda color, or sugar content in the carbonated sodas is responsible for the buoyancy of the sealed cans. This Activity can be used as an introduction to density in a middle school physical science course, or a high school chemistry or physics course.

## Colorful Lather Printing

In this Activity, students marble paper with shaving cream and food color while exploring water, polarity, and hydrophilic and hydrophobic materials. Although the Activity is familiar, it contains a new twist—exploring how a colored shaving cream mixture behaves when a drop of water is added. This Activity can be used to introduce the concepts of polarity, soaps, and surfactants.