Mini-pat: a model cellphone tower

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Figure 1
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Figure 2
Your village is about to get cellphone coverage. A cellphone company is planning to build a tower on a hill next to your school. Once the tower is built, the people in your village will be able to use cellphones. For example, they will be able to phone the doctor, clinic or chemist when they get sick. Everyone is very excited and they can't wait to phone their family members who live far away!Some people are worried that the tower will look ugly. They think that it will not look nice next to the school, that it won't fit in with the surroundings. They would prefer a tower that does not look like a tower.
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Figure 3
  • Read the story above the picture at the top of the page again, then look at the pictures of six different cellphone towers in Chapter 10. Which of those towers will make the people in your village happy?


  • The cellphone company sends one of their employees to the village. He talks to the people in the village to find out what the designer should keep in mind when she makes plans for the tower. So he asks you:

    "What are the three most important things I have to keep in mind when I design the cellphone tower for your village?"

    You can start to answer by saying: "The tower must be . . ."

    You can also start parts of your answer by saying: "The tower must not . . ."

    Write down your answer below. You can mention more than three things if you want.

    By writing your answers to the question, you have started to write a design brief and specifications for a cellphone tower.


  • Look at the picture of the village on the previous page. Where do you think the cellphone tower should be placed? Also decide what type of tower it should be, and make a rough drawing of the tower on the right place in the picture.

  • Your model should be more than 30 cm tall.
  • It should have a flat platform near the top of the tower. In a real tower, technicians will stand on this platform when they install or fix the transmitters and receivers at the top of the tower. The platform on your model should not be larger than a 10 cm by 10 cm square.
  • The model should fit in with the surroundings. It must be camouflaged in some way.
  • The model should be made from strong materials so that it will be stable.
  • It should also be rigid and hold its shape.
  • Your model should be reinforced using triangulation.
  • You can use any suitable building materials for your structure, such as materials that can be found around your home. Examples are stiff reeds; thin, straight sticks; or hand-rolled paper dowels.
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  • Write the design brief.

    1. What is the problem?[1]


    2. Who will be happy about the new tower?[1]


    3. How will it help them?[1]


    4. Now write the design brief. Use the answers of the questions you have just answered. Start your paragraph with:

      I must design and make... [2]

  • Identify the specifications.

    1. How should the tower be designed so that it will not look ugly?[1]


    2. What should be at the top of the tower?[1]

    3. Write down another specification, in your own words. [1]


    4. Write down another specification, in your own words. [1]


    5. Write down one more specification, in your own words. [1]


  • Identify the constraints.

    1. At least how tall should your model be? [1]


    2. How much weight should your model be able to carry? [1]


    3. You can only use materials that you can find around where you live. What are these materials? [3]


  • camouflage.

    Camouflage means to cover or colour something to make it look similar to, and fit in with, the things around it.

    Tech1_LG_gr7_ch12_fig4.tif
    Figure 4: Some insects camouflage themselves very well
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    Figure 5: An animal that camouflages itself well
  • How will you camouflage your tower?


    Towers are designed so that they are stable, strong and rigid.

    • Something is stable if it does not fall over or collapse easily. The opposite of stable is unstable.
    • Something is strong if it does not break easily. The opposite of strong is weak.
    • Something is rigid if it does not bend easily. The opposite of rigid is flexible.
  • How will you make sure that your model cellphone tower is stable?


  • How will you make sure that your model cellphone tower is strong?


  • How will you make sure that your model cellphone tower is rigid?


  • Tech1_LG_gr7_ch9_fig33.tif
    Tech1_LG_gr7_ch9_fig33.tif
    Show both of your designs to each other.
    Tech1_LG_gr7_ch9_fig33.tif

    Will the materials bend too easily?
    Will the tower fall over easily?
    Will the tower be strong enough to support the platform at the top?
    Will you have all the materials you need to build your model?

  • how frame structures are reinforced to make them stronger and stop from bending
  • how frame structures are prevented from toppling,
  • the important features you identified when you investigated towers.
  • the need to avoid visual pollution.
  • Tech1_LG_gr7_ch9_fig33.tif
  • When the design is poor. If you make a bucket with a hole in the bottom, it will not hold water. The water will run out through the hole. The structure cannot work as it should, and it cannot do the work it was designed for.
  • When the wrong materials were used. The materials used for a structure must be strong enough for the load the structure has to carry. A child's chair will break when an adult sits on it, because the materials were not made to carry such a heavy load.
  • When the workmanship is poor. When the handle for the pan you fry your food in is not firmly fixed, it will break off. Poor quality workmanship can lead to your hand getting burnt.
  • You will need:
  • handmade paper straws,
  • glue (you can make your own - use the recipeon the right),
  • wire,
  • a thin card,
  • sticky tape or masking tape, and
  • a nail or an awl.
  • Home-made glue

    1 cup flour

    ⅓ cup of sugar

    1 ½ cups of water

    1 big spoon vinegar

    Mix the flour with sugar in a pot.

    Add half of the water. Stir.

    Add the rest of the water and stir.

    Add the vinegar.

    Heat the mixture until it gets thick and shiny.

    Leave the mixture to cool.

  • Partner 1 makes joints A, B and E.
  • Partner 2 joins straws, as shown in C and D.
  • Partner 3 joins three straws with a paper "gusset", as shown in F.
  • Work carefully with hot things, a stove or open flames.
    Use a thick cloth or pot holder to prevent burning yourself or others.
    If you get burnt, hold the burnt area in cold water for 20 minutes.
    Do not rub anything on the burn.

    Tech2_LG_gr7_ch12_fig6.tif
    A. Joining two straws by pushing one straw into the other one
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    B. Joining two straws by pasting with glue
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    C. Using wire to make a joint
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    D. Using a card gusset to strengthen a joint

    Use tools safely
    Use tools for the purpose they are made for. Scissors are made for cutting - not for anything else.
    It is also important to use tools correctly. If you have not used a tool before, ask someone who knows how to work with it for advice. Keep tools in good working order and pack them away after you have used them.

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    E. Making and using triangular card gussets to strengthen a joint
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    F. Making, cutting and pasting three-dimensional card joints
    Figure 6
  • You have already made a design for a cellphone tower. Look at it again. Make a list of everything you will need to build the model.

  • The tools and materials that are needed to build something are called resources.

  • Make a working drawing of your model on the next page. Your drawing should show what the model will look like from one side. Use a ruler and show dimensions. The drawing should be half as big as the model will be. Label your drawing to show the different parts. Show what the parts and the joints are made of.

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  • You should choose a design that the team can make. Choose the best design or make up a new design that uses ideas from every team member.
  • It is important to draw the design well.
  • Everyone should understand exactly what the team will make before you can move on to the next step.
  • Remember that your design must include a platform on which workers can stand when they work at the top of the tower.
  • Someone in the team has to sketch the new idea on a clean sheet of paper. It can be a rough sketch. It should show the materials that will be used and how the joints will be strengthened.
  • Make your own drawings of some joints in the space below. Also make a copy of the drawing of the whole tower on the next page.
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    Tech1_LG_gr7_ch9_fig33.tif
    "planning to make".
  • Make a list of all the materials you plan to use to build your model. (2)


  • Make a list of the tools you will use to build the model. Even a nail to make holes with can be called a tool. (2)


  • Think of your safety when using tools. Some tools can be dangerous if they are used incorrectly. Write down one safety rule for one of the tools you will be using. (2)


  • Think about the order of work. This is a list of all the steps you follow when you make the model. Below is the first step. Add a few more steps. (4)

    Step 1. Roll straws from scrap paper.

    Step 2.


    Step 3.


  • First build the tower without the platform.
  • Which joints will I make?
  • Which joints worked the best?
  • Which one is best for our model?
  • Which materials will we use for the joints?
  • Are you going to make a frame structure for a base?
  • Are you going to use a foundation? What will you use, a piece of cardboard or polystyrene?
  • Ask yourself if the tower will topple over, and if it will be able to carry the weight of two A5 textbooks.
  • Make sure that the tower stands upright and does not fall over.
  • Build the platform and anchor it to the top of the model tower.
  • Test if your tower can carry the weight of two A5 text books.
  • Camouflage your model. Don't forget that your tower must fit in with the surroundings.
  • Criteria for working drawings

    Tick

    The drawing has a heading.

    The heading includes the view that the drawing is drawn in, which is the front view.

    The outline of the drawing is darker than the dimension lines.

    The dimensions have only been written down once.

    The dimensions (measurements) are written in millimetres. You don't have to write mm, because designers always use millimetres on working drawings.

    All measurements are placed in the centre of the dimension line.

    Arrowheads are neatly drawn on either end of your dimension lines.

    The drawing is neat.

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    Figure 7
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    criteria.

    Criteria are ideas you use to judge something.

  • Change each of the criteria into a question you will ask, and write the question in the evaluation sheet below. Work as a team.

    • Your model should be no less that 300 mm (30 cm) tall.
    • It should have a flat platform on the top. In a real tower, such a platform is used by engineers when they need to work on the top part of the tower. You will use two A5 textbooks to test if your tower is strong enough to hold the radio transmitters and receivers.
    • The model should fit in with the surroundings. It should be camouflaged in some way.
    • The model should be made from strong materials to keep it stable.
    • It should also be rigid and hold its shape.
    • Your model should show reinforcement through triangulation.
  • Criteria

    Good
    3

    Medium
    2

    Poor
    1

  • Work on your own. Use the evaluation sheet on the previous page to evaluate the tower you and your teammates have built.

  • Join your teammates and compare your evaluations. Discuss it and try to agree on a final evaluation.

  • Write your questions into the following two evaluation sheets. You will use these sheets to evaluate towers built by other teams.

  • Criteria Model of team A

    Good
    3

    Medium
    2

    Poor
    1

    Criteria Model of team B

    Good
    3

    Medium
    2

    Poor
    1

  • Plan your presentation.

    • All the team members have to talk aboutthe work they did when they built the tower.
    • One learner has to show and explain thedesign sketch. Tell the group how you plannedto make the tower fit in with the surroundings.
    • One learner should talk about the problemsthe group experienced.
    • One learner should talk about how thegroup tested the tower.
    • Decide who will start and who will talk next.
  • Use the space below to write notes about what you will do.

  • Hints for presenting

    Stand up straight and look at the class when you speak.

    Do not read your presentation.

    Speak clearly, so that everyone can hear you.

    Know when it is your turn to speak.

    Keep to the time limit.

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