Wednesday, March 25, 2009

Studying the Heart

We are continuing to work our way through the body using Blood and Guts and The Body Book, and it's been great! The heart model, however, was a bit of a disappointment.

The Body Book model is constructed with a single top layer containing all the structures that opens up to reveal a bisected heart with vessel connections. I had them color the vessels based on oxygenated v. deoxygenated blood, not as arteries and veins. The model has several problems. The inner heart is not the same size or shape as the outer layer. The aorta is not labeled, and the three vessels coming off the top of the aorta (going to the upper extremities and the head) do not line up so when the top flap is closed it looks like there are four vessels. The labels on the pulmonary veins (the smaller red structure coming into the left atrium) are upside down. And when the pulmonary artery is lined up to match the outer layer, the part glued onto the inner hear covers over the pulmonic valve. Perhaps these errors were corrected in the Scholastic release of the book.
The book does come with two coloring sheets, one for the entire circulatory system and another a series of pictures depicting how the heart fills with blood.

The kids had fun with the activities from Blood and Guts. It comes with instructions to build a stethoscope, but why do that when you can just borrow your mom's real stethoscopes? Ds#1 and Ds#2 are listening to their brother's heart sounds (S1 and S2, or lub dub.) We also checked out most of the pulse points on the body at rest and after running up and down the hallway 10 times.

Ds#2 pulled this book of the shelf for us to read "because it goes with what we studied," he said. The Let's-Read-and-Find-Out science books are his favorite right now.

Friday, March 20, 2009

Journey North Mystery Class progress

With the equinox here, we saw some really interesting data for Journey North today. So interesting we decided to spend most of our school day exploring it.

Pictured is our photoperiod graph. As you can see, all the photoperiods from around the world are converging around the 12 hour mark for the equinox.

We were also told that sunrise today in Greenwich, England was 06:03 UT (Universal Time, a.k.a. GMT) then given a table with the sunrise in UT for our 10 mystery classes we are trying to find. It takes the earth 4 minutes to move 1 degree west, so we could calculate our longitude based on this information. I made the calculation for all 10 locations, though the one we're focusing on is E 6.5 degrees (we already figured out from our photoperiod that it was N 4 degrees.) It looks to be in Cameroon, which for our family was quite special since the Pope wrapped up his visit to that country just yesterday.

Tuesday, March 17, 2009

Windows to the Universe

Windows to the Universe is a wonderfully rich web site put together by the University Corporation for Atmospheric Research at the University of Michigan is not only a source for a wealth of astronomy information, but for a lot of general science with some social science and history as well. And content is still being added.

One of the more intriguing features for registered users (free) is the ability to create online journals. I as a teacher create an account and enter in one or more "classroom" names. My kids can then register to create their own journals linked to my "classroom."

Once they create a journal, they of course can type in their own text, plus they can browse the site to add graphics and links with as little as two clicks (the journal is restricted to links and images from that site only.) I can create a "public" journal for my kids to read, or an assignment for them to complete using their journals. You can even print them out to keep.

Monday, March 9, 2009

The Dart Award of cultural, ethical, literary, and personal values

I am honored to have this award presented to me Miss Julie's Place - Art Lessons for Kids! If you have not seen this blog, and I hadn't until this award, it is worth checking out. I also received it from, another outstanding blog.

“This award acknowledges the values that every blogger shows in his/her effort to transmit cultural, ethical, literary and personal values every day.”

What is neat about this award is that it started out in Spanish blogs and jumped to English several months later. Another blogger traced it and posted the findings. The text was so small it was illegible, so I made it visible, putting words that reflect its origins. I love the graphic.

It has been passed on to anywhere from 5 to 15, so anyone who receives this can choose however many to whom they would like to pass it.
  1. Talking to Myself
  2. Totus Tuus Family & Catholic Homeschool
  3. In the Sparrow's Nest
  4. Rockhound Place
  5. Four Little Monkeys

I would also have passed this on to Our Journey Westward and to School for Us except they already got it from Julie!

I'm looking forward to see to whom you all pass this on...

Saturday, March 7, 2009

Science Saturday Challenge #6

Tinkering With Inertia

Newton's first law of motion describes inertia: a body a rest will stay at rest, and a body in motion will stay in motion in a straight line at a constant speed unless either is acted upon by an outside force. We read about inertia in the Dynamics section of the Usborne Science Encyclopedia (pg. 122.) This is not just a linear property, but a rotational one as well.

We used Tinker Toys to explore rotational inertia. (You could also do this with clay and dowels if you want.)

Ds#3 is holding two Tinker Toy configurations that use the exact same pieces. I had the boys hold each one in the center and twist it back and forth, making the top and bottom swing back and forth like a pendulum. I asked which would be easier to swing; they thought the one with the weights at the ends would be.
They were surprised!

The farther the weight, the greater the inertia, so the harder it is to move.

Ds#2 is showing our next experiment. Here I asked the boys to try and balance this structure on their palm. They tried it with the weight closer to their palms...

...and with the weight farther away from their palm. They predicted the first position would be easier to balance.

They were surprised again!

As in the first experiment, the farther the weight, the greater the inertia, so the harder it is to move.

Next Ds#1 is demonstrating another structure that I had them balance on one finger. You see that his finger is at the center of the structure with equal weights in each end.

I asked what they thought would happen if I moved the weight in on one side. Ds#2 thought the side with the closer weight would be heavier, and Ds#1 thought the other side would be heavier. The toy fell towards the weight that was farther away. In the picture, Ds#1 shows that he had to move his finger so that it was midway between the weights, not the middle of the bar, to balance the structure.

Here gravity is acting on the mass creating a force; rotational force is called torque, which is a force exerted at a distance from the axis of rotation. The longer the arm, the greater the torque.

I then showed them how this all relates to something common: a seesaw. I asked which end of the seesaw they would rather have to lift. At first they thought the side with the closer weight, but after a moment they changed their mind.

This time they were right!

Just like the second experiment, a fulcrum is the axis of rotation, so the longer the arm the greater the gravitational torque.

We then played with the Torque and Moment of Inertia Gizmo. Torque equals the force multiplied by the distance from the fulcrum:
T = r F

Even without knowing actual values, you can see that the farther the weight is (the greater r is) then the greater the torque is. If you have to lift a weight using a fulcrum, like a seesaw or a pulley, you certainly don't want the short end of the stick!

Another example of this is when skaters spin. With their arms out, the center of mass is farther from the center and the spin is slower than when they bring their arms close to their bodies. This is also why two balls of the same mass but different size will roll down an inclined plane at different rates. The smaller ball rolls faster since less energy has to be spent to overcome the rotational inertia.

For an advanced discussion, see Fizzics Fizzle.

Thursday, March 5, 2009

Free Science and Math Webinar April 1st

Maureen Wittmann, author of For the Love of Literature that lists hundreds of living books by subject, is offering FREE webinars. And the next one, on April 1st, is about teaching math and science with living books.

The webinars is Bringing Joy to Your Homeschool Math and Science Lessons and are offered through Homeschool Connections Online. Space is limited so register in advance for this wonderful event.

All you need to participate in a webinar is a computer with speakers (or headphones.) You watch and listen to the speaker, and you can type in questions for her to answer live, all in your pajamas if you want! You can get an idea by viewing one of her past webinars, and see what wonderful suggestions she has.

Homeschool Connections Online offers free webinars, and it is starting to offer, for a modest tuition, classes for middle and high school students.