Towers and Parachutes

Week 3 introduces us to the famous legend of Galileo dropping objects from the Tower of Pisa.  We completed the student exploration guide of the ExploreLearing Free Fall Tower Gizmo.  Another free tower simulator, Galileo Drops the Ball, and many other science simulators are available from SEED.

Before starting the Gizmo I gave a simple demonstration.  I took a feather and a ball and asked which would fall faster; then I dropped a small toy and a large toy.  Some were surprised that the second set of objects hit the ground simultaneously.  Next I dropped a book and a sheet of paper, and they fell at different rates.  Finally, I placed the sheet of paper on top of the book and dropped them; they fell at the same rate.  That got them thinking about concepts that they could explore further with the Gizmo.

After learning about air resistance, terminal velocity, and vacuums, I gave the 3 physics groups a challenge.  They each needed to build an egg parachute that met two criteria.  First, the egg had to fall without breaking; second it had to fall more slowly than a rock dropped simultaneously.

Each of the three groups were all successful, and had very different designs.  The older boys used a large sheet of newsprint for the parachute and a thick cardboard cone to hold the egg.  It's a good thing it didn't rain that day...

The girls covered fabric with lamination, adding in straw stays for the parachute and along the strings; they had a foam cube for the harness, decorated with flowers.  It fell the fasted of the three, but still slower than the rock.

The younger boys used a trash bag for a parachute and a cut up egg carton for the harness, with a good amount of duct tape to hold it all together.

I gave them two weeks for construction.  The day of the drop was very windy.  All the kids (21 of them) gathered for the event.  You can see the videos of each parachute being dropped out a window, a team member dropping the parachute and an adult dropping a rock.

Pendulums

Our third week of co-op we performed the pendulum experiment described in the book.  We had three fishing weights (labeled 1, 2, and 3), three lengths of string, and a stopwatch. I created a data sheet (link goes to Google Docs) for them to fill in; they will need three of them to record data for the entire experiment.

This is one experiment in which the kids are very much surprised by the results.  They expected that lifting the weight higher up would increase the time for 10 swings; they also expected a heavier weight to make a difference.  Only the length of the string matters.

Related Gizmos:  Period of a Pendulum and Pendulum Clock

Ellipses

We are working our way through Objects in Motion: Principles in Classical Mechanics by Paul Fleisher. The first lesson is about Kepler's Laws of Planetary Motion.

A key moment for Kepler was when he abandoned circular orbits for elliptical ones, so I designed an activity around ellipses.  I cut a large foam board into quarters, one for each student, and tacked paper to it.  They put two push pins along the horizontal midline of the paper, slipped a string with the ends tied together over it, and drew an ellipse by drawing the string taut with a pencil and circling the push pins.  They moved the pins progressively farther, then closer, and observed what happened to the ellipse.  We discussed how a circle is a special form of an ellipse, just as a square is a special form of a rectangle.

I then discussed Kepler's Second Law and shaded in a pie piece away from the sun and close to the sun.

For the elementary group we skipped the third law.  For the middle school kids I simply wrote the formula and we discussed what it meant, including exponents and proportionality.  They got the fact that distant planets orbit more slowly and related that to the force of gravity.

If you use ExploreLearning Gizmos like we do, there's one on Ellipse and another on Kepler's Laws.

Discount for Upcoming Live Online Immunity Class

I will be teaching a six-week class on the immune system for high school students called Immunity in Sickness and in Health.  The class runs from January 17th until February 21st, Mondays from 1:30 to 2:30 live over the Internet.  All you need is a computer, headphones, and a microphone.  The course costs $90, with a $15 discount for early registration if you register before November 1st.

Physics with Secrets of the Universe

This year we are focusing on physics, and I found a great series of books to introduce middle school students to the subject.  I am using it with our co-op as well.  The series is Secrets of the Universe by Paul Fleisher.  Originally published as a single volume, it is now available as 5 slim books, perfect for moving from elementary into middle school science.  We have started with Objects in Motion: Principles of Classical Mechanics.

This series has so much to like about it.  Fleisher explains concepts in a clear manner with informative examples.  He tells the story through the scientists who first discovered the principles bringing an interesting historical perspective.  He intersperses experiments throughout the text rather than as a separate section.  The graphics are simple and of a single color, yet effective.  It really is a pleasure to read!

The other four books in the series are Liquids and Gases: Principles of Fluid Mechanics; Matter and Energy: Principles of Matter and Thermodynamics; Waves: Principles of Light, Electricity, and Magnetism; and Relativity and Quantum Mechanics: Principles of Modern Physics.

Our TORCH co-op is now up to 6 families and 21 children.  I teach 3 sections of physics, one for middle school girls (4 of them), another for middle school boys (4 of them), and another for older elementary boys (3 of them).  I plan to blog more about out experiences soon!