17 minute read
Teacher Guide
Grade Level
Secondary, grades 9-12
Time
7-14 class periods depending on the length of class periods and the activities you choose to conduct
The magnets in the Model Wave Generator are very strong. In order to separate them, students should slide/twist them apart. Please also take the following precautions: Wear safety glasses when handling magnets. Use caution when handling the magnets. Fingers and other body parts can easily be pinched between two attracting magnets. When students set the magnets down they should place them far enough away from each other that the magnets won’t snap back together. When you are finished with the magnets and ready to store them, put a small piece of cardboard between them. Keep magnets away from your computer screen, cell phone, debit/credit cards, and ID badges. Do not allow the magnets near a person with a pacemaker or similar medical aid. The magnetic field can affect the operation of these devices.
Magnet Safety
&Background
Water moving in the oceans has a large amount of kinetic energy. Marine Hydrokinetics (MHK), also known as Marine Renewable Energy (MRE), involves the use of technology to harness this energy from the oceans to generate electricity to power our lives. MHK incorporates power from ocean surface waves, ocean currents and tidal movements, and even the power produced from thermal and salinity differences throughout the waters of the world. Your Future in Marine Hydrokinetics is an exploratory unit for secondary students in a CTE classroom environment that includes teacher and student guides containing comprehensive background information on energy, the properties of fluids and waves, electricity, hydrokinetic technologies, and specific skills needed in the future MHK/MRE field. Students will review energy forms and sources, electricity generation and transmission, water movement in the oceans, and the technology under development to utilize the energy in ocean waves, currents, and tides. Activities included have been curated with a CTE classroom in mind and can be easily modified according to the skill level of the students. The curriculum includes hands-on, inquiry-based explorations, group presentations, and cooperative learning activities. Many of the materials suggested can be gathered from a craft, hobby, or sporting goods store, and are substituted easily with similar materials found in your classroom and beyond.
Concepts
Energy exists in many forms, and those forms can be transformed into other forms. We use ten energy sources for our energy needs; five are renewable and five are nonrenewable. Electricity is generated when a coil of conducting wire is moved in an electric field, or when magnets are moved through or around a coil of conducting wire. Electricity can be generated using the energy found in tides, ocean currents, and waves. Marine hydrokinetic technologies are primarily experimental or developmental. When MHK technology is ready to be installed on a utility scale, many geographic and environmental factors must be considered. When MHK technology is ready to be installed on a utility scale, there will be a great demand for people trained to pilot the vessels specifically designed to install and maintain the equipment.
@Science Notebooks
Throughout this curriculum, science notebooks are referenced. If you currently use science notebooks or journals, you may have your students continue using these. A rubric to guide assessment of student notebooks can be found on page 13 in the Teacher Guide. In addition to science notebooks, student worksheets have been included in the Student Guide. Depending on your students’ level of independence and familiarity with the scientific process, you may choose to use these worksheets instead of science notebooks. Or, as appropriate, you may want to make copies of worksheets and have your students glue or tape the copies into their notebooks. The rubric can also be used to evaluate student work in this format.
2Preparation
Read the Teacher and Student Guides thoroughly and decide how you are going to implement the unit in your classroom. Obtain the materials needed for the hands-on activities using the materials list on page 5. To save time and anticipate student struggles, you may want to assemble one Science of Electricity Model prior to using it with the class. Become familiar with the operation of the model and the other equipment in the kit, especially the multimeter. Directions for using the multimeter are included on Student Guide page 30. A more detailed discussion of multimeters and measuring electricity can be found in this guide on pages 17-19. For Discovering MHK Technology, decide if you will have students build models that actually generate electricity or that are visually illustrative only. Preview the three parts of the CTE Model Wave Generator and decide how you will approach them. Part 1 can be done as a teacher demonstration while Parts 2 and 3 work well as small-group activities. However, if you have a small class, you might want to have them work as one group on the entire activity. The tubs of water needed for the CTE Model Wave Generator should be sufficiently deep such that student models can be submerged and move freely, but small enough to be pushed to generate waves. Placing thick wooden dowel rods or pieces of PVC pipe beneath the tub can make generating waves easier.
Activity 1: Electricity and Magnetism
&Background
Generating electricity involves capitalizing on the principles surrounding electromagnetism. As one of the four fundamental forces of nature, electromagnetism allows us to use changing magnetic fields to induce electric current in a conductor. The two parts of this activity allow students to explore electromagnetism and see its effects.
Objectives
Students will be able to explain how electricity and magnetism are related. Students will be able to demonstrate electromagnetism using at least two different devices.
Materials PER STUDENT GROUP
9-volt battery Compass Nail 2 DC motors 2 Alligator clips Disassembled motor Shake-light flashlight Masking tape Electricity and Magnetism worksheets, Student Guide pages 26-27
2 Preparation
Gather materials for student use. If appropriate, assign reading Student Guide pages 2-8 as a homework assignment the night before you conduct the activity. Prepare copies of the handouts as needed.
Procedure
1. Introduce the activity to students. Explain that electricity and magnetism are related. Go into as much or as little detail as is appropriate for your students. Have students read pages 2-8 in the Student Guide. 2. Forewarn students that leaving the alligator clips attached to both terminals of the 9-volt battery in Part 1 essentially short-circuits the battery, draining it of its energy and making it get very hot. In some cases, 9-volt batteries left to short-circuit have ruptured.
Advise students to connect the alligator clips to the second terminal only when they are ready to test the electromagnet. 3. Allow students sufficient time to complete both parts of the activity. 4. Have students reconvene as a large group. 5. Using a shake-light flashlight, talk about its operation and explain how the parts contribute to its operation. Ask students which parts are important for generating electricity and which parts are used to create light. This will be important when students conduct Part 1 of the CTE Model Wave Generator in a later activity.
¨Extensions
If your students are already familiar with the basic concepts of electromagnetism, have them go further into what factor(s) affect the strength of an electromagnet. They can investigate number of turns around the nail, thickness of wire used, size of the nail, voltage of the battery, and so on. The strength of the magnet can be demonstrated by the maximum distance at which the magnet will act on another object, such as a paper clip or another nail. Understanding how the variables contribute to electromagnet strength will help students understand how transformers work and the variables surrounding increasing power output of a generator or alternator. Have students use digital multimeters to calculate the power used by the motors in Part 2. Pages 17-18 contain a detailed explanation of using multimeters to measure electricity. Provide additional batteries or DC power sources and motors of varying sizes and have students investigate the power used by them. An investigation such as this will help students understand the relationships among voltage, current, power, and motor size.
Activity 2: Science of Electricity
Objective
Students will be able to demonstrate and describe how electricity is generated.
1 Small bottle 1 Rubber stopper with ¼” hole 1 Wooden dowel (12” x ¼”) 4 Strong rectangle magnets 1 Foam tube 1 Small nail 1 Large nail Magnet wire Permanent marker 1 Pair sharp scissors Masking tape Fine sandpaper 1 Push pin 1 Multimeter with alligator clips Hand operated pencil sharpener Ruler Utility knife Science of Electricity instructions, Student Guide pages 28-30
! Caution
The magnets used in this model are very strong. Refer to page 6 of this guide for more safety information. Use caution with nails and scissors when puncturing the bottle.
Materials PER STUDENT GROUP
2 Preparation
Build one Science of Electricity model for student reference and to help you assist your students in the trickier parts of the build. Gather materials for student use and prepare copies of the instructions as needed.
Tips for Assembly
You may want to pre-sharpen the dowel rods or slice rubber stoppers in half width-wise, using half on each side of the rotor, to make assembly easier. To streamline the process of winding wire around their bottles, have them thread a pencil or dowel through the wire spool and have one student hold this in their hands while another student winds wire. Before students wind wire around their bottles, have them tear several 5 cm pieces of masking tape and have them hanging off the edge of their table or lab bench as they work. Students can tape their wire coils as they go to prevent a seemingly catastrophic, spontaneous unspooling of wire. One tip of a large, sharp pair of scissors can be inserted into the hole in the bottle to shave away some of the plastic so the dowel turns freely. The dowel needs to be able to spin unimpeded. When connecting the sanded ends of magnet wire to alligator clips, have students wrap the wire around the clips. Otherwise, the fine wire may pull easily from the alligator clip.
Procedure
1. Introduce the activity. Demonstrate the model you have already assembled, explaining the various parts. 2. Divulge to students the areas in which you struggled a bit, explaining how you overcame those struggles and providing tips to help them be successful. 3. Allow students enough time to assemble their models. If one class period is not sufficiently long enough, make sure students have wrapped all of their wire coils before stopping for the day so they do not lose track of where they were. 4. After students have finished building and testing their models, ask them how their models compare to the simple DC motors they worked with in Activity 1. 5. Discuss with students how their models, and the DC motors they worked with in Activity 1, are the same as utility-scale generators, and how they are different.
¨Extension
You might want to build your model according to the student directions, and then have students modify the model to use a different container, or varying numbers of magnets or turns of wire, and compare their results. Challenge students to design a model that produces electricity in greater amounts than your model did.
Activity 3: Discovering MHK Technology
&Background
Marine hydrokinetic technology is a rapidly evolving field. This activity provides an opportunity for students to explore the different technologies currently in development. It also gives students the opportunity to hone their modeling skills by asking them to build a representative model of the technology. Because of the speed with which MHK technology is being adapted and developed, the same group of students could engage in this activity in sequential years and not repeat their research or findings.
Objectives
Students will understand the different technological areas of MHK generation currently in development. Students will be able to build a model of a device given its description and photographs or drawings.
Materials
The following materials are suggestions of the kinds of things students can use to build their models. Teachers are encouraged to utilize what they have available without incurring significant additional expense. Craft wood Small screws, nuts, bolts, other fasteners Repurposed materials such as plastic bottles, yard signs, etc. Craft materials such as foam, plastic, wire, etc. Display boards and art supplies (optional) DC motors (for electrified models) Digital multimeters (for electrified models) Discovering MHK Technology worksheet, Student Guide pages 31-32.
2 Preparation
Spend some time using internet resources to read about the most prominent MHK technologies currently under development. Decide if you will pre-assign students to groups or if you will allow them to form their own small groups. Determine how much in-class time you will devote to the activity, and how much must be done outside of class. Make a physical or digital copy of the worksheet with resource links for students. Make a list of the technologies you wish students to investigate and decide the manner in which you will assign them to student groups. Gather supplies for students to use to build their models and/or make their presentations.
Procedure
1. Have students read Student Guide pages 9-23. This can be done as a pre-reading homework assignment. 2. As a class, summarize the information students have read. 3. Present the activity to students, giving an overview of what the activity will entail. If students will be electrifying their models, explain to them how that will be accomplished. 4. Assign student groups the technology you wish to have them explore. 5. Preview the internet resources listed on the student worksheet. If you are providing others, preview those as well. 6. Give students time to start planning their presentations and designing their models as a group. 7. As students work on their projects, they may need assistance or suggestions as they build their models and finalize their presentations. 8. Before students present their models, provide them with the rubric or grading scheme you will use to score them. 9. After all of the presentations are completed, have a class discussion about which technology they believe will be most feasible at utility-scale.
Notes
Students with limited internet access outside of school should be allowed time during the school day to gather information and work together on their presentations. This can be accomplished by devoting some entire class periods to this task or by providing part of each class period on sequential days. Decide if you will allow power tools, and if so, under what circumstances students will use them. Because waterproofing can be a significant challenge for students building electrified models, testing models should be done using air pushed by fans as the energy source rather than flowing water. Advanced students can be instructed in building waterproof models. If you have a 3-D printer available for student use, this project can be a great way to help students hone their 3-D modeling and printing skills.
¨Extensions
The models and presentations students develop are great for community outreach or a parent night. Have students investigate which technology, if any, would be appropriate to install within your school community. If your community is not located near any large bodies of water, choose a place on the map to explore. Collaborate with a social studies teacher to discover the cost of each type of technology and whether it is appropriate for implementation in a developing country.
Activity 4: CTE Model Wave Generator
&Background
Wave energy is accessible any place there is a very large body of water; it is not limited to just oceans. The Great Lakes and inland seas also have waves sufficient in size to be used to generate electricity. Wave generators take advantage of the steady oscillation of waves in an up-and-down, or rocking, motion. This activity shows students a working device in the form of the shake-light flashlight, then challenges them to build two models, one horizontal and one vertical, that generate electricity from wave action. Objectives
Students will understand the variables that affect the voltage a generator can produce. Students will understand the relationship between electricity and magnetic fields. Students will be able to build, test, and modify a design given a specific problem or set of parameters. Materials
PART 1 MATERIALS 2 Shake-light flashlights 1 Heavy-gauge, zip-close, plastic bag large enough to hold one flashlight Alligator clips Digital multimeter or galvanometer Empty 1-gallon water jug, with cap Utility knife Balance PART 2 MATERIALS PER STUDENT GROUP Clear plastic tubing Two rubber stoppers Magnet wire 1 Cylindrical magnet Alligator wires Digital multimeter or galvanometer PART 2 MATERIALS FOR THE WHOLE CLASS TO SHARE At least 1 large tub of water, 4-5 gallons or more; clear containers are better but not necessary. Hot glue guns and extra glue sticks Fine-grain sandpaper Parafilm or other means of waterproofing PART 3 SUGGESTED MATERIALS Clear plastic tubing Cylindrical magnets Fishing line Hot glue gun Magnet wire Pool noodle, Styrofoam, or other buoyant materials Sandpaper Fishing bobber or floats Galvanometer Waterproof duct tape Repurposed plastic containers Heavy objects for anchoring Alligator clips
2 Preparation
Read through each part of the activity. The first two parts build up to a design challenge activity where students design, build, and test their own wave generator models. To save on materials and cost, you may choose to do Part 1 as a demonstration and discussion rather than individual or small group activity. Prepare copies of the handouts as needed.
Notes
It may be helpful to have pieces of large wooden dowel or thick-walled PVC under the tub of water to facilitate a rocking motion to produce consistent waves. One great way to waterproof your students’ models is by using a thin layer of paraffin. Parafilm is a commercially available product that is a thin layer of paraffin on waxed paper and often found in chemistry laboratories. Application of parafilm involves simultaneously stretching and wrapping the film. The wax film sticks to itself when stretched and pressed gently. Part 3 has students designing their own models that are oriented vertically. Page 46 of the Exploring Marine Hydrokinetics Student Guide has directions for building a working model using the suggested materials. It may prove helpful if you review this activity to provide some tips or suggestions if students are struggling to design their own models. When students are designing their vertical generator models in Part 3, it is important to keep the diameter of the coil such that the magnet is very near it. Use cylindrical magnets that are just a bit smaller than the inner diameter of the tubing you provide. While students might choose different materials or designs for their vertical generators, they will not get any measurable output if the coil of wire is too far away from the moving magnetic field.
Procedure
1. Have students read the informational text about wave energy generation in the student guide on pages 11-13. This can be assigned as homework the night before the activity. 2. Work through Part 1 with students. You may decide to do all of the steps yourself while students watch, or you may decide to have each student do one step at a time while you read or provide instructions. 3. Ask students about buoyancy and why it’s important to this model, and then to scaling up this model to utility-scale generation. 4. Introduce Part 2. Explain that students should design and build a model very similar to the flashlight that will be water-tight and float without needing the plastic bag. Allow students enough time to complete Part 2. 5. Discuss the results of Part 2 with students. Ask them to compare their results to the results of Part 1, and the functioning of Part 2 as compared to Part 1. As a class, discuss and work through issues students encountered. These issues may arise in Part 3, so it’s important to discuss them here. 6. Introduce Part 3. Show students the materials you have prepared for them to use. This part of the activity is designed to be a designtest-modify process. Remind students to change only one thing at a time when modifying their designs so they know which change(s) yield the greatest improvement. 7. When students have finished, discuss their results. Project or draw a table similar to the one shown below and allow students to identify and discuss the pros and cons of horizontal and vertical designs.
DESIGN PROS CONS
HORIZONTAL (ROCKING) GENERATOR
VERTICAL (BOBBING) GENERATOR
8. It’s simple enough to build a small-scale model such as the ones in this activity. However, scaling a model up to utility-scale generation is quite another story. Ask students what kinds of materials they think a large-scale device based on their models might employ. Discuss the problems they think engineers might encounter when scaling up to utility-scale generation.
