Instead of just sliding objects on an air table, the Activity Object shows clearly what each block represents in our basketball situation, as shown in the scene below. This helps students establish the real-world connection.

Then the rich scaffolding begins. First students join different orange blocks, the spring, and the red block, and set them in motion by releasing the compressed spring. Students have to examine the data for which physical property (mass or volume) is important in determining the block’s speed. The analysis of data indicates that the mass is important.
After the exploration, an explanation describes momentum, and explains the equation and units for momentum. In the elaboration phase, students now tackle the driving question of the basketball players. The students now join the orange and red blocks with a spring but also place the blue block on the table. When the blocks are launched, the orange block moves to the left, the red block to the right where it collides and joins with the blue block. Just as in the starting investigation, students see the actual motion of the blocks, so the data they explore is more meaningful. Then the momentum of each block (orange, red, and red joined with blue) is calculated, and all of these momenta are the same. This helps students to progress in their understanding of conservation of momentum.

This understanding is further developed with an animation describing conservation of momentum. Then students are introduced to other applications of Newton’s Third Law and momentum, including rocket launches, automobile-truck collisions, and Newton’s cradle. After the Activity Object, a ten-question multiple-choice evaluation helps teachers know which concepts students have mastered and where they may need additional work. There is a well-designed Enrichment Sheet for homework where students read a few paragraphs and then answer questions about momentum and solve problems.
As wise of a man as Vic Mayer was, I’m still not sure that all hands-on activities are simulations but I do know that some simulations are better, more economical, and easier than other simulations. “Conservation of Momentum in One Direction” shows the power of a virtual simulation in scaffolding and developing deep understanding of concepts, using the 5E learning model, and helping students realize how classroom science concepts apply to their lives.

Today is Labor Day (thus the casualness of it all) and my son and his friend were shooting some video segments of, well, shooting as well as backwards slow motion (see http://www.youtube.com/user/YouKnowMeHy). I asked them to film a demonstration I did this week at an inservice professional development workshop I did for middle grade teachers.

My son filmed with his little Sony Cyber-shot camera (a still picture camera that also does video) and then edited it with Apple’s iMovie.

For another discrepant event please visit my blog posting on surface area to volume ratio.

When it comes to science supplies, you can be sure that measuring devices such as stop watches, scales, rulers, and graduated cylinders will be useful. There is risk however in purchasing other materials, as you wonder will they work.

It all started well with my Sprout and Grow Window kits that I purchased for my elementary sciencemethods classes. They planted the generous supply of pea plant seeds that the kit provided. And in 5 of the 6 windows we had healthy germination. The plants looked neat growing up out of the thin plastic container housing the roots.

But the window idea paid no dividends. Although it was possible to see some small roots amid the very dark soil, it was disappointing how little you could actually see. I took one of the kits home to care for the plants. About one week after we started the kits, I planted the same pea plants in my home garden. Last week I took pictures of pea plants in the kit and in my garden. Our home telephone is put into each picture for scale.

Garden pea plants with phone at bottom

I know this is not a carefully controlled experiment. Nevertheless, clearly the outdoor garden plants did much better than the window indoor plants. Most people would guess that would be the case, even in a “winter” in Phoenix (where we have so far managed to avoid a seriously deadly frost). But without the benefit of being able to view the roots well, you have to wonder, why would you want to use the Sprout and Grow Window kits? So this review, gives these kits a rating of only 1 out of 4 test tubes. In other words, I don’t recommend that you purchase the product.

But it is nice that the pea plants they supplied grew so well outdoors. I have never grown peas before and I must confess I felt a connection to Gregor Mendel as I saw my plants rise up and flower. I even have pea pods starting to form. I think I will hold off on any genetic crosses for the time being but I think I might be up for a virtual experience at Adaptive Curriculum’s “Mendel’s Experiment.”

From the Activity Object "Mendel's Experiment" by Adaptive Curriculum

When I was doing my sabbatical at the University of San Carlos (Cebu, Philippines), Ed Van den

Berg (one of the really great guys in science education), would have the undergraduate secondary education science students put on physics and chemistry demonstrations for the local school children. It was a delightful way to give them experience teaching and expose children to the interesting world of science. In the picture, two of my students demonstrate their fire tornado. (See http://www.west.asu.edu/rillero/philippines.htm for more of my photographs from the Philippines.)

In this YouTube video below, a similar program is described called “The Little Shop of Physics.”

The electronic Ohaus scales that I ordered a few years ago are slowly dying. Only half the digits are readable on the numeric displays or in some cases there are no readable numbers. At NSTA in Phoenix, I stopped by the Ohaus booth and the representative was not surprised when I told her this. Unfortunately, she informed me, the scales have only a one-year warranty. From the initial lot we bought, half are unusable.

Using the scales in our science methods classes at Arizona State University, shouldn’t be taxing compared to ordinary high school, middle school, or elementary school use. So it surprised me that the LD50 (a biology term for half a population dying) was achieved so quickly. But maybe my expectations are out of line, our Honda Odyssey, my wife informed me today, has 170,000 miles on it. But a one-year warrant, really? That makes me wonder how confident the manufacturer is in their product.

I like how fast the electronic balances gave readings. No longer were drafts, fast walkers, or table shakers an issue in our classroom, as compared to the old reliable triple beam balance scales. I predicted the end to triple beam balances at the high school and an even quicker death to the elementary level pan balances. But, perhaps I was too hasty.

I am not sure if Ohaus scales are worse then others. The sales rep informed me that in the newer models, the problem has been addressed with the displays. That won’t benefit me; I will put my next order in with a different company. But she also told me of another issue that seems likely to affect most scales that are not top end. Adding too much weight can permanently damage the weighing device. Yikes! It seems like a common occurrence, especially when doing full inquiry experiences, that students would add too much weight. Indeed, it seems like there should be warning signs on the scales about maximum loads.And this brings up a final issue. Why is it that we can’t find good reviews of science apparatus? I have bought things that are great and things that are lousy; wouldn’t it be nice to have a place like CNET that helps us tell what is good and what is not. But if you have scale advice, please do leave a comment.