Hand Model Category: Biology: Human Body; Kinesiology; Physics: Force & Motion Type: Make & Take Rough Parts List: 10 10 5 10 Craft sticks Straws 12” pieces of string Beads Cardboard Tools List: Scissors Needle or paperclip Hot glue gun Pencil Needle nose pliers Video: https://youtu.be/Kbfr48OKlYo How To: Trace your hand onto cardboard. Cut out the palm of your traced hand. Glue five craft sticks onto the palm. Place the sticks so they barely stick over the edge of where your fingers should be. © 2015 Watsonville Environmental Science Workshop. All Rights Reserved worldwide. When linking to or using WESW content, images, or videos, credit MUST be included. Cut four craft sticks into three equal parts. Cut a fifth stick into two parts. These represent the bones in your hand. Cut a straw piece for every cut piece of craft stick. Cut the straw pieces slightly shorter than the cut sticks and glue them on. Glue one straw onto each craft stick on the cardboard hand. These represent ligaments. Turn over the cardboard hand. Glue the small craft stick and straw segments onto the straws. © 2015 Watsonville Environmental Science Workshop. All Rights Reserved worldwide. When linking to or using WESW content, images, or videos, credit MUST be included. Cut five additional small straw pieces. Glue them onto the top edge of the cardboard palm. Wrap masking tape around the sticks and straws. The tape helps to keep the small segments from falling off. Tie a bead onto one end of each string. The strings represent tendons. Use a needle or open paperclip to pull a string through all the straws in one finger. Tie another bead onto the free end of the string. Pull down on the strings to watch the fingers move. Fine Points: → It takes a long time to finish an entire hand and many students are not able to complete the whole thing. To get around this, students can built a finger model instead. → Put the hot glue on the craft stick, not the drinking straw, or the straw may melt. → Note the our thumbs have one less bony segment than all our other fingers. Concepts Involved: •
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Bones provide the structure of our hands. There are few muscles in our hands – muscles in our arms pull on tendons to move the hands. Tendons connect bones to muscles. Ligaments connect bones to other bones. © 2015 Watsonville Environmental Science Workshop. All Rights Reserved worldwide. When linking to or using WESW content, images, or videos, credit MUST be included. Focus Questions: 1.
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What parts of your model represent the bones in your hand? Ligaments connect bones to other bones, what part of this model represents ligaments? Tendons connect bones to muscles, what part of this model represents tendons? What are some differences between the model hand and your hand? Human hands have two sets of tendons, one in front of the bones and one in back. What do you think the tendons in back do? Elaboration: Our body moves when our muscles pull on our bones. Ligaments attach bones to bones, and tendons attach bones to muscles. Most of the muscles that pull on each segment of your fingers are actually in your forearm. If you put your hand palm up on the table and move one finger at a time, you can see narrow lengths of muscles move in your forearm. Each of these muscles is connected to one bone in your hand through long tendons. The tendons move from the arm to the hand through the carpel tunnel. In science, models help you understand the real thing. A model is similar to the real thing, but every model has its limitations. As you work with a model, you must always think about what is similar and what is different from the real thing. There are several major differences between this model and a real hand. For each of your fingers on your hand, there are actually three muscles, one for each of the three bones. You usually use them all together, so like most people you are probably not able to move a single bone in, say, the tip of a finger. Also, when you stop bending a finger, it doesn’t snap back the way a model finger does. You also have another set of muscles and tendons going down the back of each finger to re-­‐
extend it on demand. If a tendon breaks, sometimes a doctor can repair it. Ligaments are more difficult to heal. The ligaments in this model are the long straws connecting the bones in the back of the finger. Muscles, bones, tendons, and ligaments always work together, and if there is too much force put on the system, any of them may break. Links to k-­‐12 CA Content Standards: Grades k-­‐8 Standard Set Investigation and Experimentation: Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other strands, students should develop their own questions and perform investigations. Grades k-­‐12 Mathematical Reasoning: 1.0 Students make decisions about how to approach problems: 1.1 Analyze problems by identifying relationships, distinguishing relevant from irrelevant information, sequencing and prioritizing information, and observing patterns. 1.2 Determine when and how to break a problem into simpler parts. 2.0 Students use strategies, skills, and concepts in finding solutions: 1.1 Use estimation to verify the reasonableness of calculated results. 1.2 2.2 Apply strategies and results from simpler problems to more complex problems. 1.3 Use a variety of methods, such as words, numbers, symbols, charts, graphs, tables, diagrams, and models, to explain mathematical reasoning. 2.5 Indicate the relative advantages of exact and approximate solutions to problems © 2015 Watsonville Environmental Science Workshop. All Rights Reserved worldwide. When linking to or using WESW content, images, or videos, credit MUST be included. and give answers to a specified degree of accuracy. 3.0 Students move beyond a particular problem by generalizing to other situations: 3.1 Evaluate the reasonableness of the solution in the context of the original situation. 3.2 Note the method of deriving the solution and demonstrate a conceptual understanding of the derivation by solving similar problems. 3.3 Develop generalizations of the results obtained and apply them in other circumstances. © 2015 Watsonville Environmental Science Workshop. All Rights Reserved worldwide. When linking to or using WESW content, images, or videos, credit MUST be included.