When I was a doctoral student in Science Education in the 1990s at The Ohio State University, Vic Mayer (1933-2011) was on my committee. He was a fabulous science educator and a role model for all who were in the program. As a proponent of hands-on science, it perplexed me when he said one day, “All classroom hands-on science is a simulation of real science.” I could partially see his point: clearly many hands-on activities were simulations, especially when contrasted with having students examine real data sets that seem common in the Earth Systems sciences, which Dr. Mayer loved. Yet I wondered, why isn’t looking at cells through a microscope real science?
When it comes to air tracks and air tables for doing physics investigations, these clearly are simulations. They are also very expensive simulations with the cost of one group’s materials approaching $1000 when you factor in the track or table, air source, photogates, and other materials. So a class set of the materials can easily approach $7000. It would be great to have lab technicians keep the apparatus fine-tuned but alas that responsibility typically falls upon the physics teacher. The point of any simulation is to help students understand real concepts, such as momentum.
I was delighted to experience Adaptive Curriculum’s Activity Object “Conservation of Momentum in One Direction.” The Activity Object begins with an animation of two basketball players throwing a ball back and forth, and then being put on ice skates. Now, the players move backwards as they throw the ball forward (Newton’s Third Law). Students are now engaged by the question, why did the player on the left move more than the player on the right?

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.

Living just north of Phoenix, we get the warm sunny 70° January weather, but we can drive 100 miles to the north to play in snow. Snow takes on a reverent beauty when you are just visiting it, playing in it, and having the air full of thick, downy flakes. When it makes unwanted intrusions, such as when I lived in New York, Ohio, and Iceland, it becomes more difficult to appreciate.

To the right you will see some snow fun pictures from our snow play in Flagstaff yesterday. It is interesting to see the evolution of “sledding”. Even in my childhood, toboggans were on their way out. Wooden sleds with two rails and a steering bar, like the Flexible Flyer, ruled the hills. I didn’t even see one of these on the hills.  The disc or flying saucer seems to be waning.  The flexible-foam, body length “sled” is the new king of the slopes. But what slides down the snow best?

The “coefficient of friction” (COF) is used to express the amount of friction between surfaces and this is proportional to the force pushing the surfaces together, or the weight of the rider and sled on the snow. The greater the COF the more friction there is. The COF for not-yet moving surfaces (static friction) is greater than sliding surfaces (kinetic friction). Engineers have measured different COFs (link). For instance, the kinetic COF for leather on oak is 0.52 and for those interested in glass-on-glass action, the kinetic COF is 0.4. Google has enlightened me. I had no idea there was so much research done on snow, and that there is a vibrant field called “snow engineering”, which might be called the ultimate snow job.  Without going too deep into it, the COF for a moving skier (ski on snow) was analyzed to be between 0.01 and 0.3. I’d have to think that metal on snow would be a lower COF than foam on snow. It is good to think about, and students could do some fun experiments to find out.

Virtual science experiences must engage students and must have rich interactions. If it is just a Flash animation, I am not ready to call it an “experience” when the term video is much more suitable. If a teacher is going to bring laptop carts into a room or sign up weeks ahead for the computer lab, they should have computer-learning experiences that feature an engagement, a significant interaction, a closure, and multiple means of assessment. 

“Sliding on Different Surfaces,” an Activity Object by Adaptive Curriculum, features these aforementioned characteristics. For an engagement, students play a game where they steer a sled down a hill while encountering different types of surfaces. If they steer over the surfaces with the least amount of friction, they will go faster. They receive a score based upon how well they did.

In the student interaction, students are in an office. They slide a pencil case across a desk and then mark the distance. Their mission is to find different things in the room such as a towel, newspaper, and sandpaper (obviously a rough office)  and see how the pencil case sliding distance varies.  (Elearning Physics Preview)

This elearning physics experience moves forward to an explanation of friction and factors that influence friction. There is an optional paper-and-pencil activity sheet that students can complete as they do the Activity Object, with two questions to be answered when they are finished.  The activity sheets promote writing and become a permanent record of their learning for their science notebooks. If a teacher has a projector or interactive whiteboard and is doing a whole class lesson, the activity sheet is even more essential.

After the closure, students move onto the multiple-choice assessment, where they answer five questions and receive instant feedback about their learning. Teachers can log in to access student scores for the assessment. They can also see how long students took doing the Activity Object. If students are up for a bit of gaming, with their new understanding of friction, they can go back to the game and improve their time.

I did the Activity Object and played the game, and I observed that compared to my 8 and 11 year old sons, my sled in Flagstaff went much farther than their sleds. I would like to think that this was because I selected the patches of snow with the least friction and thus I picked up more speed. But these foam “sleds” are not very steerable and so, unfortunately, I have to consider the competing hypothesis that since my mass is a wee bit more than my sons (well okay, actually my weight is about 50 pounds more than both of them together), this may have had an influence. Since momentum is equal to mass x velocity, my momentum should be much greater than my sons’, and thus it would take longer to bring me to a stop. An impulse (force x time) can change the momentum of an object. Since my momentum is much bigger, and assuming that friction is about the same, I coast longer and thus farther.

But I think I will choose the happier hypothesis – that my greater knowledge of friction, rather than greater weight, made me go farther. Which just goes to show the subjective side of science after a happy family day in the snow.