The school year is well under way. But before students enter science labs, they must turn in a safety acknowledgment form.

After completing introductory safety training, as noted in NSTA’s Duty of Care (NSTA 2014), review and have students and their parent or guardian sign a safety acknowledgement form (see Resource), stating safety practices and protocols. In addition, test students on the safety training before they begin any lab work.

It’s important to know the difference between a safety acknowledgement form and a safety contract. Generally, a teenager can enter into a legal contract at age 18, so younger students should only be asked to sign a safety acknowledgment form. By signing a safety acknowledgment form, students confirm that they have been informed that the lab can be an unsafe place, and that they have agreed to follow safety procedures and protocols.

The science teacher needs to keep the original copy of the forms on file for the duration of the class. The statute of limitations for negligence in most states is three years from the date of harm. If there is an accident in the classroom or lab, the teacher should compile safety information records, including the acknowledgement form and accident report, and provide copies of the records to his or her school district. In the event of an accident, these documents should be kept until the statute of limitations run out. In some rare cases, when parents refuse to sign the safety acknowledgment form, teachers need to date, sign, and note the fact that the parent refused to sign the form.

Once the lab investigations are under way, science teachers also have the responsibility to:

1. Inspect for safety before, during, and at the close of activities, and monitor student behavior and equipment to help foster a safer learning environment.

2. Enforce appropriate safety behavior and apply a well-defined progressive disciplinary policy, which involves a progression of steps, starting with a verbal warning and escalating to removal from class.

3. Follow-up on maintenance to ensure engineering controls and personal protective equipment are operational and meet the manufacturers’ standards. If the ventilation cap on a chemical splash goggle has been removed, for instance, take the goggle out of operation.

Submit questions regarding safety in K–12 to Ken Roy at safesci@sbcglobal.net, or leave him a comment below. Follow Ken Roy on Twitter: @drroysafersci.

Reference

National Science Teachers Association (NSTA). 2014. NSTA—Duty or Standard of Care. www.nsta.org/docs/DutyOfCare.pdf

Resource

Safety acknowledgment form—www.nsta.org/pdfs/SafetyInTheScienceClassroom.pdf

NSTA resources and safety issue papers

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As with all sports, skateboarding involves a lot of intriguing physics. I’ve marveled at the maneuvers of skilled skateboarder Alex Hewitt (my grandson). When traveling along a horizontal surface, Alex crouches and then springs upward with his skateboard to continue horizontal motion along a nearly half-meter-high elevated surface (above).

He could easily do the same while wearing roller skates, which would be no big deal because the roller skates would be attached to his feet. But in no way is his skateboard so attached. So how does the skateboard manage to follow him along his upward trajectory? Furthermore, by what means does the board gain gravitational potential energy with no applied upward force and no apparent loss in kinetic energy?

This amazing feat bothered me because it seemed to contradict the laws of physics. I then watched a slow-motion video of Alex to learn how he does it.

Figure 1. The downward force on the tail of the board rotates the board upward.

Exerting a torque about the axis of the rear wheels
The leap that Alex executes is called an ollie, a blend of the physics of linear and rotational motion. While heading for the elevated surface, he crouches and springs directly upward while exerting a downward force on the tail of the board that produces a torque about the rear wheels. (Torque = force × distance about a rotational axis.) This quick downward snap of the tail, with or without its making contact with the ground, causes the board to rotate upward into the air (Figure 1).

The same thing happens when you give a sharp tap to the rounded end of a spoon lying on a table. The spoon flips up into the air, just as Alex’s skateboard does. The center of masses of both the spoon and board are raised by this snap-and-flip action.

Figure 2. The downward force by the front foot on the nose of the board counters the first rotation produced by the back foot.

Exerting a second torque about the board’s center of mass
Controlling lift goes further. While the airborne board rotates upward, Alex slides his forward foot toward the nose of the board and produces a second torque, in the opposite direction (Figure 2).

This second torque raises the tail, puts the board in contact with the back foot, and levels the board before it meets the elevated surface (Figure 3, below). So we see the results of two torques, one that flips the board upward and one that levels it off. Skillfully executed, this sequence enables Alex and his skateboard to meet the elevated surface.

Energy conservation
The kinetic energy of Alex and his skateboard before and after the ollie is practically the same. Yet he and the board have gained substantial gravitational potential energy as the board rides atop the elevated surface. Does the ollie maneuver violate the conservation of energy? No, it does not. Here’s why: First, the energy that propels Alex himself is straightforward. By crouching and leaping, he converts bodily chemical energy into mechanical energy just as if he had jumped up from rest.

But what about the board? From where does it get the energy to move upward and follow Alex? The answer involves the work-energy

Figure 3. The counter rotation levels the board for a horizontal landing.

principle of mechanics (work done = change in energy). For straight-line motion, work = force × distance moved. For rotational motion, work = torque × angle moved.

Alex does work on the board when he produces a torque that flips it into projectile motion. As with all projectiles, acquired kinetic energy converts to gravitational potential energy.

Another explanation, the simplest, bypasses rotational mechanics and energy conservation. The force that Alex exerts on the tail of the board as he jams downward on it is significantly greater than both his weight and that of the board. In action-reaction fashion, this downward push produces an upward normal force (the perpendicular support force) that is also greater than the combined weights of

Figure 4. The normal force N propels Alex and the board into projectile motion.

Alex and the board (Figure 4). This increased normal force launches both Alex and the board into projectile motion.

One of the beauties of physics is that puzzles often have more than one explanation.

Hooray for the conservation of energy and for skateboarding in general. ■

Paul G. Hewitt (pghewitt@aol.com) is the author of the popular textbook Conceptual Physics, 12th edition, and coauthor with his daughter Leslie and nephew John Suchocki of Conceptual Physical Science, 6th edition.

On the web
See complementary tutorial screencasts on physics by the author at www.HewittDrewIt.com. Watch Alex execute the ollie in slow motion in screencast 42 at http://bit.ly/Alex-ollie.

Editor’s Note

This article was originally published in the October 2016 issue of The Science Teacher journal from the National Science Teachers Association (NSTA).

Get Involved With NSTA!

Join NSTA today and receive The Science Teacher, the peer-reviewed journal just for high school teachers; to write for the journal, see our Author Guidelines and Call for Papers; connect on the high school level science teaching list (members can sign up on the list server); or consider joining your peers at future NSTA conferences.

The mission of NSTA is to promote excellence and innovation in science teaching and learning for all. Learn more about the Next Generation Science Standards at the NGSS@NSTA Hub.

Future NSTA Conferences

2016 Area Conferences

• Minneapolis, Oct. 27-29
• Portland, Nov. 10-12
• Columbus, Dec. 1-3

“At what age can a child begin science learning?” asked one participant at an early childhood education workshop on investigating the properties of water in a fun, scientific way using observation, documentation and reflecting on that work. The group answered the question, “As infants,” “My babies do,” and “At any age,” just as I put this photograph on the screen:

The educators work in diverse programs, from Head Start to Montessori to their own child care programs in their own homes. About half of the Early Childhood Care Education workforce cares for and teaches children outside of formal child care centers and preschools (NAS 2012 pg 114). I began my career in early childhood education as one of the educators who care for children in our homes, a family child care provider. At this workshop most of the educators were immigrants and their education was a varied as the countries of their birth, and we came together in our shared passion for understanding how young children learn. Everyone participated, making and playing with small drops of water (thank you Young Scientist series!); pouring, scooping and splashing water; using tubes, funnels and frames to create systems to move water; and discovering how cups with holes in various positions can also create systems (thank you UNI’s CEESTEM!). We talked about safety first, liquid/solid, noticed the “stickiness” of water, explored displacement and the force of moving water. It was fun! I’d like to claim that it was my skill as a presenter that kept the group engaged but it was their curiosity and desire to continually improve so they can be even better teachers for the children in their care.

As we worked, the group discussed their ideas about science concepts and shared how to help the parents of the children they care for understand how children learn through experiences. As always, I appreciate the generosity of this education community—they listen to each other, ask questions to get the most out of the session, share materials and their expertise, and help clean up at the end.

Reference

National Academy of Sciences (NAS). 2012. The Early Childhood Care and Education Workforce: Challenges and opportunities. Appendix B Summary of Background Data on the ECCE Workforce. Washington, D.C.: The National Academies Press.

https://www.nap.edu/catalog/13238/the-early-childhood-care-and-education-workforce-challenges-and-opportunities

In the September issue of The Science Teacher, we wrote about the new standards for digital skills established by the International Society for Technology in Education (ISTE). Now, let’s look at how the standards can be applied to science content.

This month, we discuss the Empowered Learner standard, which requires that “students leverage technology to take an active role in choosing, achieving, and demonstrating competency in their learning goals, informed by the learning sciences.” To accomplish this standard, students should meet these four performance indicators:

• Engage in personal goal setting that includes reflection,
• Develop the ability to build a network to support their learning,
• Use technology to receive feedback in different forms, and
• Understand and troubleshoot technology.

Meeting the performance indicators

Goal-setting is a critical part of the learning process. SMART Goal templates, often used in business, can ensure that students are developing personal goals. Students can use blogs (e.g., WordPress), journaling tools (e.g., Evernote), or even “media diaries” (e.g., Fotobabble and Photo 365) to share their thoughts or reflect on their goal achievement and learning. Changes to thoughts or understanding can also be seen through the evolution of student writing via track changes in Microsoft Word or revision history in Google Docs.

To become an empowered learner, students must build a network to enhance their learning. Twitter can be a powerful tool to build and grow learning spheres. Point your students in the right direction by creating a class account used to follow science-related people and groups. When starting your Twitter network, consider following NASA (@nasa), Earth Science Week (@earthsciweek), NSF Earth Science
(@NSF_EAR), and Neil DeGrasse Tyson (@neiltyson). After establishing the classroom’s virtual networks, allow students to customize their learning environment with flexible and moveable classroom arrangements, such as furniture, which foster a collaborative and “networked” classroom.

Empowered learners should be familiar with the feedback many technology tools inherently provide. It is important that students recognize the value of “adaptive learning tools,” such as Knewton, as a means to grow and develop in any content area. It is equally important that students draw upon technology tools’ interaction and peer feedback capabilities found in resources such as Google Docs, VoiceThread, or Padlet. With those commenting tools, students can share thoughts about the instruction, conclusions drawn from a lab investigation, or predictions about a future event, while quickly receiving comments from other students, teachers, or experts in the field. No matter the tool, however, gathering peer feedback develops the communication skills necessary for the requirements of this standard.

None of the performance indicators are possible without a basic understanding of how technology tools work, so that technology never serves as a barrier or distraction to learning. To illustrate the supportive nature of technology and understanding how the tools fundamentally work, use Chrome Extensions with students. Students must understand that the Chrome browser is a power productivity tool that can be enhanced by Extensions and Apps to improve learning, perform tasks, and enhance their work. As an example, head over to the Chrome Web Store and search for the “periodic table.” You will quickly find both apps and extensions that can be valuable for students.

Conclusion
The Empowered Learner standard allows students to develop an independence and responsibility for their learning. As students mature and advance their skills in this area, they will be ready to tackle the rest of the standards. In the next issue, we will examine the role that digital citizenship plays and the responsibility that all educators have to foster it in their classrooms.

Ben Smith (ben@edtechinnovators.com) is an educational technology program specialist, and Jared Mader (jared@edtechinnovators.com) is the director of technology, for the Lincoln Intermediate Unit in New Oxford, Pennsylvania. They conduct teacher workshops on technology in the classroom nationwide.

Editor’s Note

This article was originally published in the October 2016 issue of The Science Teacher journal from the National Science Teachers Association (NSTA).

Get Involved With NSTA!

Join NSTA today and receive The Science Teacher, the peer-reviewed journal just for high school teachers; to write for the journal, see our Author Guidelines and Call for Papers; connect on the high school level science teaching list (members can sign up on the list server); or consider joining your peers at future NSTA conferences.

The mission of NSTA is to promote excellence and innovation in science teaching and learning for all. Learn more about the Next Generation Science Standards at the NGSS@NSTA Hub.

Future NSTA Conferences

2016 Area Conferences

• Minneapolis, Oct. 27-29
• Portland, Nov. 10-12
• Columbus, Dec. 1-3