Separating Mixtures

Purifying components with physical processes.

Students will make a mixture of rice, sand, iron filings, and salt, measuring the amount put in by weight or volume. They will then use different laboratory processes (filtration, dissolution, magnetic extraction) to separate out the individual components and will measure the amount they recover. We will discuss how mixtures are made without breaking molecular bonds, so that the mixed substances can be extracted again without chemical reactions.

Activity dates: 4/13/2023

(BFSU connection: lessons A9, A14)

Surface Tension

Exploring the effect of surfactants on surface tension.

Students observe how surface tension can hold a large drop of water together and how the effects of surface tension are reduced by the addition of soap. They also experiment "popping" the surface layer of water: making currents by forming a sufrace tension gradient. These currents are used to make tie-dye patterns in milk.

Activity dates: 3/9/2023, 4/23/2020

Diffusion in Fluids

Spreading through Random Walks and Density Gradients

Students will run simulations (rolling dice) to demonstrate how the random jiggling of molecules in a solution leads to diffusion: the spreading of particles from high concentration to low concentration regions. By comparing transit times, they will see that diffusion across longer distances becomes very slow. We will also note that density or gradients can allow for faster spreading as solute molecules push each other out of a dense region. By watching the movement of colored dye away from dissolving skittles, students will observe how solute molecules spread out rapidly from a region of high density and then mix much slower by random-walk diffusion once the density gradient is gone.

Activity dates: 3/2/2023, 11/18/2020

(BFSU connection: lesson A11)

Fluid Viscosity and Drag

How Fluids Resist Flow

Students will buld a simple viscometer and use it to compare the flow rates and viscosities of different common fluids. They will then gain first-hand experience with viscous drag, by pulling a paperclip through fluids with a weak magnet at different speeds. Large drag forces due to fast speeds or high viscosities will rip the paperclip off the magnet. The maximum achievable speed can be compared among the fluids and will vary according to their measured viscosities.

Activity dates: 2/16/2023, 5/14/2022

Float versus Sink

Density of fluids

Students will measure densities of common fluids and learn that objects with lower density than the surrounding fluid will float. They will make a density column with three fluids and several common objects, predicting the order of the layers and the location where each object floats. They will then make their own "lava-lamps" with floating gas bubbles and sinking water droplets in a tube of oil, powered by an acid-base reaction.

Activity dates: 2/9/2023, 4/23/2022

(BFSU connection: lesson A15)

Density of Materials

Measuring mass, volume, and density

Students will learn about the concept of density as the mass per unit volume of an object. We will identify the material that pennies and dimes are made off by comparing them to pure metals. We will also compare densities of glass, plastic, metal, and rock and identify the true nature of a seemingly `golden' rock, a la Archimedes. This activity will introduce students to the use of scales and graduated cylinders, and to the notion of measurement precision and error.

Activity dates: 2/2/2023, 4/23/2022

(BFSU connection: lesson A15)

Gasses: Pressure and Volume

Pushing around air and blowing up balloons

In this activity, students demonstrate that air takes up space by using a cup as a diving bell. We find two different ways of blowing up a balloon without touching it, by increasing pressure or decreasing it through suction. The relationship between volume and pressure is applied to build a simple model of our lungs, where increasing the volume of a container (chest cavity) lowers the pressure and brings in air from the outside.

Activity dates: 1/26/2023

(BFSU connection: lesson A3, A6)

States of Matter

Solid, fluid, and in between

Students examine solid and fluid materials, demonstrating that solids undergo elastic deformation in response to small forces and fracture in response to large ones, and that fluids tend to maintain a constant volume. They then make a batch of Oobleck -- a viscoelastic material that behaves as a solid in response to short rapid forces and as a liquid in response to slow forces.

Activity dates: 1/19/2023

(BFSU connection: lesson A2)

Rotational Inertia

Spinning Tops and Rolling Races

Students gain hands-on intuition for rotational inertia by manipulating spinning toys and by making batons with different mass distributions. They set up races for rolling objects of different shapes (hollow vs solid), relating the rate of rolling to the distribution of mass around the spinning axis. Applications of rotational inertia in sports are discussed.

Activity dates: 10/27/2022

Kinetic and Potential Energy

Marble Roller Coasters

Students experience the conversion between kinetic and gravitational potential energy by constructing simple tracks for rolling marbles. Conservation of energy and the loss of mechanical energy due to friction are discussed. Students measure the maximum height of loops and hills that a marble can get over from a given starting height.

Activity dates: 10/20/2022

(BFSU connection: lesson C3)

Forces and Flight

Taking Off with Paper Airplanes

Students explore the forces produced by moving air that help an airplane fly. They will experience drag and lift forces directly with paper sheets. They will then make their own paper airplanes and examine how different control flaps affect the behavior of the plane.

Activity dates: 10/13/2022, 5/14/2021

(BFSU connection: lesson C8)

Center of Mass

The Amazing Floating Butterfly

Students will discover how the center of mass serves as the "balance point" of an object. They will find the center of mass of a cut-out butterfly and learn how to shift that center so that the butterfly can be balanced on its extreme tip. They will also explore how placing the center of mass underneath the support allows an object to be in stable equilibrium.

Activity dates: 10/6/2022, 2/12/2021

(BFSU connection: lesson C9)

Gravity and Projectiles

Time and Range for Projectile Motion.

Students explore what factors affect how long it takes an object to fall and how far it flies while falling. A sound recording app is used to precisely measure times of flight. We learn that gravity makes heavier and lighter objects fall vertically at the same rate, regardless of how far they move horizontally.

Activity dates: 9/29/2022, 5/7/2020

Mass and Weight

Measuring the force of gravity

Students will make their own spring scale to measure forces. Using pennies as a standard mass, they will demonstrate that the force with which gravity pulls on an object goes up with the mass of the object. The distinction between mass (amount of material) and weight (force of gravity) will be discussed.

Activity dates: 9/22/2022

(BFSU connection: lesson C3A)

Newton's Laws

Exploring forces and inertia with balloon rockets.

Students create balloon rockets that zip across the room. We discuss how jet propulsion works, and explore the effect of mass on how quickly the balloons move. A pendulum is used to see the effect of inertia as the balloon rockets speed up and slow down.

Activity dates: 6/4/2020, 9/15/2022

(BFSU connection: lesson C5, C7)

Inertia

Exploring motion

Students will become familiar with Newton's 1st Law, demonstrating that objects sit still or keep moving with a constant velocity until something pushes them. We will see inertia in action by watching rolling marbles and dropping objects while on the move.

Activity dates: 9/8/2022

(BFSU connection: lesson C5)

Diffusion and Random Walks

Simulating Intracellular Transport

Students will use simulations and model systems to explore how particles move through fluids in the intracellular world. First, we will simulate diffusion by mapping out random walks with dice, demonstrating how inefficient diffusion can be for transport over long distances. The students will then explore actively driven random walks by finding encounter times between hexbug nanobots in different conditions mimicking the crowded and geometrically complex environment inside living cells.

Activity dates: 6/4/2022

Diffraction Spectra

Patterns and Rainbows by Diffraction of Light

Students will observe diffraction spectra from light bending around a hair, and use the spectrum to compair hair thickness. Diffraction glasses are used to explore diffraction patterns and notice how different color laser beams make slightly different patterns. The glasses are then used to look at several sources of white light, noting the varying spectrum of colors in each.

Activity dates: 3/26/2022, 2/27/2020

Light Beams and Lenses

Reflection and Refraction of Light

Students explore reflection and refraction by visualizing laser pointer beams bouncing off surfaces and bending at interfaces. We will cut out our own lenses from jello to see light beams converge and diverge, and discuss the optical properties of human eyes. Students also use jello strips as "fiberoptic cables" to bounce laser beams around a corner.

Activity dates: 3/5/2022

Activity dates: 11/19/2019, 12/17/2019

Standing Waves and Sound

Visualizing string vibrations and sound

Students will investigate traveling waves by sending pulses through a stretched slinky, and try making standing wave patterns by shaking the slinky with the right harmonic frequencies. They will have a chance to "see" sound by singing into a resonating cavity and watching how the resulting air vibrations make sugar grains dance. Finally, we'll make a variety of toy musical 'instruments', including rubber-band guitars, singing balloons, and a laser-gun-noise maker to demonstrate how resonance chambers amplify sounds. Note: materials listed are for an earlier online version of this activity.

Activity dates: 1/29/2022, 12/9/2020, 12/7/2018

(BFSU connection: lesson C2)

Titration

Color-changing Acids and Bases

Students will measure the pH of different house-hold substances using a home-made red cabbage indicator. THey will then carry out a titration to compare two acids with similar pH. Predictions of relative acidity will be tested by measuring the total gas produced in an acid-base reaction and collected with a balloon.

Activity dates: 4/16/2021

Reflection and Refraction

Making Images with Light Beams

Students will visualize light beams by shining laser pointers through juice. Light beams will reflect of straight and curved surfaces, demonstrating convergence and divergence. Refraction will be explored by tracking the path of the beam at the air / juice interface, and observing the effect of a converging lens. Students will also get a first-hand look at images formed by curved mirrors and lenses.

Activity dates: 3/12/2021

Camouflage and Natural Selection

Evolution of the Skittlefish

Students will simulate how visual predation on an animal species can provide evolutionary pressure that leads to adaptations such as camouflage and mimicry. Skittles of different colors will be used to explore natural selection, demonstrating how traits in a population can change over time without any individual animal changing its characteristics.

Activity dates: 1/6/2021

(BFSU connection: lesson B5A)

Buoyancy

What determines whether an object floats or sinks?

Students will test common hypotheses for what properties determine whether different objects float (is it size? weight?) and learn about concepts of density and buoyancy. In Part 1, we explore why Legos float while playdoh sinks. In Part 2, we compare the density of eggs, water, and oil.

Activity dates: 10/15/2020

(BFSU connection: lesson A15)

Solar System

Modeling Planets

Students put together scale models of the solar system, to explorethe distances between the planets and their relative size. We discuss why scale models are useful and what sort of information they can convey. Students will develop an intuitive sense of size for the planets and the vastness of interstellar distances.

Activity dates: 5/21/2020

Fluids

Investigating properties of fluids.

Students will see how to change whether an object sinks or floats (density), what sets the speed of squirting water (pressure), and the changes in pressure that arise with fast air flow (Bernoulli effect).

Activity by: Michelle Chen

Activity dates: 4/16/2020

Viruses

Modeling virus spread

Students make a model of a virus and its lytic lifecycle, as well as simulating the spread of infectious diseases.

Activity by: Natalie Nady

Activity dates: 4/2/2020

Pendulums

What sets the regular ticking of a pendulum?

Students make pendulums and explore which variables affect their swinging frequency. They also observe resonance in action with coupled pendulums.

Activity dates: 3/26/2020

Polymers of Life: Protein and DNA

Exploring material and chemical properties of proteins from an egg and DNA from strawberries

Students learn about the physical properties of polymer solutions (viscoelastic fluids). We examine the consistency of egg whites (a dense protein solution) and how it changes when proteins are cut up by pineapple juice or unfolded by alcohol. Students then extract DNA from a strawberry using alcohol precipitation and examine its similar "slime-like" consistency.

Activity dates: 2/27/2020

Acids and Bases

Blowing up balloons with chemical reactions

Students use pH strips to measure the pH of solutions with different concentrations of citric acid. They add the solutions to baking soda, generating carbon dioxide gas which is collected in a balloon. The extent to which the balloon inflates depends on the initial pH of the solution. Measuring pH afterwards shows whether or not all the baking soda was used up during the reaction.

Activity dates: 11/19/2019, 12/17/2019