Innovation America (2007) initiative focuses on strengthening our competitive position in the global economy by improving our capacity to innovate (National Governors Association).A hallmark of a STEM literate classroom is one

where the emphasis is on design and problem solving in “intellectually messy” learning situations that weave together the disciplines.

Rigor, Relevance, Relationships

Building a Science, Technology, Engineering and Math Agenda

National Governors Association: Innovation America Task Force (2007)

States need a workforce with the knowledge and skills to compete in today’s global economy.

A new workforce of problem solvers, innovators, and inventors who are self-reliant and able to think logically is one of the critical foundations that drive innovation capacity in a state.

Key to developing these skills is strengthening math and science competencies in K-12 students.

“The science and technology standards establish connections b/w natural and designed worlds and provide students with opportunities to develop decision-making abilities. They are not standards for technology education; rather, these standards emphasize the abilities associated with the process of design and fundamental understandings about the enterprise of science and its various linkages with technology.”

NSES and Design

Set GoalsRespond to need, challenge, or problem

Build KnowledgeUse Standard Models to identify variables

DesignMeet design requirementsDetermine optimal values for variablesPlan constructionPredict Performance

Build and TestHow well does the model meet the performance criteria

Present

Design Process

Using the standard model, identify all the forces that act on the skimmer.Forward motion force: air pushing on sail from

behindFriction force: occurs between the bottom of

the skimmer and the surface it is sliding on.Torque: Air pushing on the back of the sail

creates a twisting force that acts to tip the skimmer over.

Depending on the strength and proportions of these three forces, the skimmer will either sail along, stop, or tip over.

Testing Skimmer Design

Examine the effect of each of these forces on the skimmer.

How can they be made bigger? Smaller?How can you use them to control the

skimmer’s performance: distance, stability, and speed

Identify all the variables that affect the performance of the skimmer.

Skimmer Movement

Sail AreaSail ShapeSail OrientationSail PositionSail BalanceSail StiffnessWeightReducing Friction

Variables that Affect Skimmer Performance

Sail ShapeSail Area

What is the optimal value for your skimmer characteristic?

DistanceStabilitySpeed

How do we define performance?

Maximum distanceDistance traveled in a time periodTime it takes to reach a specified targetFastest boat, slowest boat?Carry loads?Turn?

How Do we Measure Performance?

Forward Motion ForceDepends on the size of the sail. The larger the

sail’s frontal area, the greater the forward motion. Frontal area is the total area of the sail that is

perpendicular to the air flow.To get the most forward motion force out of a sail,

the sail should be perpendicular to the airflow and stiff. If the edges of the sail bend with the blowing air, they will contribute little or no force to the forward motion force.

Forward Motion Force

Symmetrical sails: the forward motion will be balanced on the left and right sides and the skimmer will travel in the direction of the airflow.

If there is more sail area on one side than the other, that side will create a larger pushing force, and the skimmer will turn toward the side with the smaller sail area: sail balance on the mastExample: A sail of 100 centimeters is mounted 1

cm off center. The left side will experience forward motion force on 60 square cm while the right side has 40 square cm. The skimmer will veer right until it has moved out of the airflow.

Forward Motion Force

Depends on the typed of material used for the skimmer and the surface it slides over.

Depends on the perpendicular force pushing the two materials together. As the perpendicular force increased, the friction increases.

You can increase the perpendicular force by using heavier construction materials, larger sail, or by adding weights (e.g., pennies).

Can you use friction to turn the skimmer?Yes, the additional weight on one side of the skimmer

will made it heavier and stick more to the surface. The increased friction on one side means the skimmer will turn to the side of the additional weights.

Friction Force

The force from the blowing air on the back of the sail creates a torque or tipping force on the skimmer that pushes the front of the skimmer down into the floor, and can tip over the skimmer

The strength of the tipping force depends on the height of the pushing force. A push on the lower back edge of the skimmer creates very little tipping force, but the pushing forces coming from the sail, some distance above the skimmer, causes the tipping force.

Tipping Force

Which sail shape will have the highest tipping force?

The sum of many little forces spread evenly over a large area is equivalent to a single force at the center of an area.

So, the strength of the force depends on the overall areas or size of the sail, but the pushing point on the mast can be thought of as the center of the sail.

So, sails with higher points will create greater tipping forces and greater sliding friction.The sail with the higher pushing point will

cause the skimmer to tip over or stop sooner.

Tipping Forces

Weight Balance Affects friction force and turning performance

Weight Affects friction force and performance of distance, speed, stability

Mast Location Front to Back Affects friction force and performance of stability

Sail Height Above Skimmer Affects tipping force and performance of stability, distance, speed

Sail Balance on Mast Affects forward motion and performance of turning and stability

Sail Shape and Center Height Affects forward motion and friction and performance of distance and

speed Sail Area – forward motion is proportional to area

What is optimal sail area? Too big and you cancel out forward momentum with friction force.

250 cm

Summary of Skimmer Features

How might you create a set of sails of different areas?

Do the test sails need to be the same shape?Why do you think it might be useful to find

the area of each of the cards?About how many times bigger in area is the 5

x 8 card and the 3 x 5 card?Do you think the 5 x 8 card would make the

skimmer go between two and three times as far as the 3 x 5 card?

Testable Questions

Can you make sails that have the same area but different shapes?

Would testing the shape of these two sails be a good way to determine the effect of sail shape:

Testable Questions cont'd

Competition in Collaborative Science Inquiry

Science Olympiad

Collaboration, Problem-solving, and Creativity

83% and 97% of males increased interest in science

Participants now believe that men and women are equally competent in science

Students learned to compromise, value other people, and work with people of different ages and grade levels

Science Olympiad