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How to make a mechanical or robotic handEstimated duration: 2 hoursAge level: Lower secondary school studentsLearning objectives, skills and competenciesThe use of tinkering and educational robotics as teaching and learning tools inside school curricula encourages students in guided discovery, in problem posing and in problem solving. Coding, tinkering, robotics and microelectronics can help to engage students in constructing useful skills and competence useful to face many kind of problems and to develop critical and computational thinking.Activities and rolesThe activity is focused on observing something in the real world, to understand how it works and making a model that can reproduce its movements or behavior. In this lesson plan the teacher asks the students to look at one of their hand to understand its movements, in order to build a prototype (a model) able to reproduce its functionality. The activity can be included in a science lesson, or in a lesson about technology, where students learn that machines and robots can help humans to do things, like handling dangerous liquids.After building a cardboard prototype, students have to motorize it using some microelectronic components (in our lesson plan we are going to use littleBitsTM kit). They can also use a LEGO Education Wedo 2.0 activity to build a robotic prototype able to grab objects and be involved in a team work, passing an object each other, by creating a code able to open their hand when a sensor put on it senses another robotic hand in front of it.The teacher will give instructions, provide explanations when needed and monitor.What do you need in order to carry out this activity?Materials to build the prototypeCardboardRubber bandsDrinking strawsAdhesive cloth tape or scotch tapeString or nylon cordGlue (or hot glue, with the help of an adult)Scissors (or cutter, with the help of an adult)Pencil or penRulerCutterPat-a FixMaterials to motorize the prototype (materials listed below are littleBitsTM kit)Mounting board9V batteryPower bit4 servo motors1 fork1 branch(Makey Makey bit)Learning spaceSchool classroom. Activity descriptionBuild the cardboard hand following the lesson plan for primary school, making sure to leave a rectangle of cardboard under the shape of the hand, in order to be able to position motors and support the prototype to keep it in vertical.Put your hand on the cardboard and draw around it with the pen; it is better to prolong the sign up to the wrist.Draw lines with the pen to divide the fingers.Cut around the outside of the hand shape and cut the lines to separate fingers.Like in the real world, it is necessary to have tendons at the back of the hand, to allow fingers to relax after each bending. Use adhesive cloth tape to attach a rubber band to the bottom of each finger, taking care especially to fix the end of each rubber band (you can leave a small amount loose, fold the rubber band and stick with another piece of tape).Stretch the rubber band slightly and then attach the other end to the top of the finger. The side with rubber bands is the back of the hand. Flip the cardboard and stick a little piece of a straw on each phalanx, with glue, and a longer piece of straw below each finger, in the metacarpus.Cut some pieces of string and tie them to the top of each rubber band, then insert them in the straws. Position the servos on the cardboard under each finger (excluding the thumb), draw their outline and cut the holes a little bit larger, to be able to fix them. Use some Pat-a Fix to make them stick, but also to be able to reuse them later.Knot the strings from the fingers to the servos and use a little piece of tape to fix them.In order to connect all servos to the power bit and the battery, it is necessary to gather them, so you can attach 3 of them to a fork, plus a fourth one to a branch. There are other ways to connect them to the power: if you want to control better the rotation speed of each motor, you should attach to each motor a slide dimmer.If you use a Makey Makey bit and some crocodile cables, you can even have more fun and code the movement of the fingers through Scratch programming. Through Makey Makey module you can connect the keys on the keypad of the computer to the littleBits inputs or outputs and control them: LittleBits modules can stick together through magnets, so it is not necessary have a previous knowledge of electronic. It is important anyway, to respect the sequence of the bit colors, when building a circuit:Blue = power modules connected to the powerPink = input modules, able to interpreter data from their surroundings. They are usually connected to output modulesGreen = output modules (like servos, LEDs, fans…)Orange = connecting modules: they can split the circuit or change direction, reverse or stop the current flow.The prototype we have built does not allow to grab objects: in order to do it, it would be necessary having an opposable thumb. You can end the lesson plan, inviting students to build a robotic hand using a LEGO Education WeDo 2.0 model able to grab objects from one point to another. (You can find the lesson plan at: ). The use of educational robotics inside the school curriculum can help the development of social skills together while simultaneously working with curricular subjects and while developing other key competences. You can experience this fact, by asking students to build their own model in pairs, adding a distance sensor and writing a program able to make the robotic hand opening its jaws IF another hand is in proximity, leaving the objects and closing the jaws, in a flow through the class. Name of author: Tullia Urschitz ................
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