Notes for teachers
If you choose to use my 10 lesson sequence as a basis for your robotics course then here are some tips to help you.
You need to be very familiar with the EV3 software and the brick interface, of course. Buy 'Classroom Activities for the Busy Teacher: EV3' in PDF and/or paper form and study the relevant chapters carefully. Be sure to work you way through all the lessons yourself, building and testing the programs, before you teach them - you will be better able to anticipate problems. If there is anything that is not clear then email me - I'd be happy to help you. I recommend that you also work through all the lessons in the EV3 Education software Robot Educator' 'Basics' and 'Beyond Basics' sections. Again - try making and running each of these programs for yourself. My pages 'The missing commentaries' will help you understand the Robot Educator lessons. It's probably OK for you to take a robot home for the weekend.
Obtain the necessary equipment
To teach the proposed 10 lessons you will need:
- Ready-made RileyRover robots, modified as below, built from the EV3 Education kits
- Ready-made attachments such as the gripper attachment and the ultrasound attachment
- A charger for each robot
- EV3 Education software installed on the computers
- Photocopies of the student worksheets for the listed lessons. One set per group, preferably assembled into a binder. Remind the students that the sheets are also available online.
- A robot enclosure (see below)
- A couple of empty Coca-Cola cans or similar, for lesson 8, 'Prepare the Landing Zone'.
- A plank, preferably flexible (thin plywood perhaps) and some books for lesson 6, 'Going Up and Going Down'. The pile of books will support the plank at one end and if the plank is flexible then it should be possible to make it bend so that the slope of the plank increases as the robot moves along it and at some point the slope will reach 20°, hopefully causing the robot to stop.
- Felt-tip pens, A3 paper and rubber bands for lesson 4, 'How many sides?'. You might also need to attach weights to the pens so that they make good contact with the paper - Plasticine might work or large metal washers could be taped to the pens. Here is a photograph showing how my students attached pens to their robots:
Organizing the equipment
I suggest you keep all the equipment (except the robot enclosure, of course) in a locked cabinet. You can keep the robots and USB cables in the plastic boxes that are included in the EV3 package, with two robots and two USB cables and/or Bluetooth dongles in each plastic box. You can keep all the attachments, the connector cables and the Coke cans in another box. You can keep the chargers in the same cabinet - it would be neat to be able to charge the robots while they are locked in the cabinet. I suggest you keep the hundreds of unused Lego pieces in a separate box which should be kept elsewhere since these pieces should not be needed and you don't want anyone mixing these pieces with your robots. I suggest that you insist that each time the students use attachments they should remove them at the end of class since it is likely that other classes will use the robots and will not need the same attachments.
Make a robot enclosure
My ICT classes have up to 16 students and we are using four robots. I have made a robot enclosure by taping together three standard tables to give total dimensions of about 1.3 by 1.8 meters. I think that is a good size for classes like mine (it is rare that all four groups will be at the enclosure at the same time). There may be slight bumps where the tables are taped together - if this is a problem then you could consider placing a large panel over the whole group of tables. I placed on this extended table a perimeter wall made of plywood - 2cm thickness and 10-15 cm height should be fine. The walls are not bolted to the tables in any way but metal plates bolted to the walls extend down beside the table tops and stops the walls moving. Don't forget to sand or file file down any sharp corners on the walls. Keep a couple of meter sticks handy on or near the table so that students can make the measurements they need. I stuck black electrical tape to the tables to act as a starting line for various exercises where the distance traveled or angle turned needs to be measured. I also have green and red paper or plastic shapes taped to the table to represent the mineral deposits that are sought after in lesson 6 'Let's go prospecting!'. Note that the colour sensor is very fussy about the colours that it is looking for - it looks for 'Lego green' (the colour of a green Lego brick) rather than just 'green' for example. So finding paper or other materials to use as coloured mineral deposits for this exercise may be difficult. My idea was to take the exact colours from photographs of real Lego bricks and then to print them as large rectangles on a quality laser printer to obtain colours that the sensor should recognize without difficulty. Here are the four 'Lego' colours that I successfully printed:
Modify the robots
My students were having a lot of trouble at first, complaining that the robot always seemed to go 'backwards'. Their idea of what was 'forwards' was based on the orientation of the intelligent brick and I agree with them - it seems to be pointing the wrong way in the RileyRover model. So I reversed the brick on all the robots and the problem went away. However, you and the students need to be aware of the modification so as not be confused by photographs of the robot in the book that show the brick oriented differently. Also, be aware that with the brick oriented 'my way' the cables to the motors no longer have to cross one another, which must be another advantage. The modified orientation is also consistent with the official standard 'driving base' model proposed by Lego.
In the RileyRover model the very expensive brick is attached to the rest of the model only by four tiny black pegs. Since the students will usually lift up the rover by lifting the brick this connection will be tested very frequently. Thus I made a second modification: attaching the brick to the rest of the model more firmly - see photos:
The neat thing about this connection is that it does not use any of the pieces that are needed for building the attachments and it does not impede the connection of the Gyro sensor or the Tactile sensor to the brick as indicated in the book.
Notes on Chapter 14: 'Going up and going down'
This chapter is especially problematic in two ways. Firstly because it introduces the gyro sensor which is more tricky to use than the others, and secondly because the book does not make it clear how to set up the ramp.
You must emphasize to the students that if the gyro sensor is not perfectly still when it is activated then its readings will drift with time and will become very inaccurate. It's a good idea to use the live sensor display in the third tab of the EV3 screen to check that the gyro sensor is giving a steady reading when the sensor is still. If this is not the case then unplug and plug in again the sensor while keeping the sensor perfectly still.
As for the slope, the idea of this exercise is that the robot will stop advancing and will reverse when the slope exceeds 20°, but the diagrams shows a slope that is constant. It seems to me that what is necessary is a curved slope and I had good success with a piece of perspex as shown below which bent under its own weight.
My perspex slope was so slippery, however, that the robot could not reach a slope of 20° so I had to adjust the challenge and use a 10° angle instead.
Prefer USB to Bluetooth connections
It is very tiresome for the students to have to frequently reconnect the robots to the computer via a USB cable each time they need to download a slightly modified program. It also means the robots cannot be kept in the robot enclosure which is supposed to guarantee their safety. Thus it may be preferable to use Bluetooth connections rather than USB. I have ordered Bluetooth dongles from Dealextreme.com for less than 2 Euros each (specifically this model) and have just spent a couple of hours trying to set up simultaneous connections between four computers and four robots, but without success (with a lot of effort I could get two connections). Perhaps with more expensive dongles it might work but I am abandoning this idea and advise you to stick to USB connections!
If you do decide to try connecting with Bluetooth then you will want to rename each brick with names like EV3-A, EV3-B etc. This can be done here:
Each group should always use the same robot
Each robot (each brick) should be clearly labeled with a letter A, B, C, D and each group should always uses the same robot. In fact the name of each group could simply be its class and the robot letter e.g. 'Class 3 group C'. There are four reasons why each group should always use the same robot:
- the characteristics of each robot may differ slightly and the students will not get predictable results if the characteristics of the robot are different each time
- it makes it easier to identify which group may be responsible for any damage
- it means the group always has access to the programs that it has saved to the brick in the past
- if you use Bluetooth to connect a computer to a robot then the connection you establish (by entering an identical key such as '1234' into both the computer and the robot) is remembered only for that specific computer and that specific robot, therefore if you use a different robot (or a different computer) you will have to go through the key validation process again.
One well-named project file per group
My experience after a couple of weeks of teaching EV3 robotics is that the bricks' memories quickly become cluttered with dozens of different projects from different groups, making it hard for the students to find their programs. Solution: each group should make only one project which should be given the name of their group (e.g. 'Class 3 group C'). Remember that only the following characters can be used for compatibility with the brick: letters, digits, space, underscore, hyphen. The students can make all their programs within that single project, giving each program a meaningful name (make sure they know that the name of any project can be changed by double-clicking its name at the top of the window). Make sure also that they know how to open the project properties panel by clicking the relevant button, shown below. In this panel students can open a program by double-clicking its name or delete a selected program with the Delete button.
Engrave and label the intelligent bricks
For 20-30 Euros you can buy an engraver which can mark all kinds of objects with the name of your school to make them less attractive to theft. I engraved the initials of my school onto each brick, sensor and charger and also engraved a unique letter onto each brick. Warning: the vibrations of the engraver could conceivably damage sensitive electronic parts. I think the risk is worth it and I decline any responsibility if you damage your equipment by engraving it.
Charging the battery
Tell the students to check the battery power level from time to time and to inform you if the battery is getting low. If you are following my course then presumably you bought the educational version of the EV3 robot rather than the home version. Therefore you are using the rechargeable battery that comes with the educational version. I have been using the robots in class for about 8 periods per week and my policy has been to recharge them all just once a week - this seems to be sufficient for my purposes. The rechargeable battery seems to hold quite a lot of energy.
After several weeks of working with the robots I have had some hardware problems:
- One of the colour sensors is not working - perhaps it never worked?
- After several weeks of use, it seemed that the ultrasound sensors were often not recognised by the brick any more, even though the batteries were freshly charged. The sensor just showed up as 'unknown' in the port view. Eventually I figured out the problem: the students had used the wait block in infrared sensor mode instead of ultrasound mode. It's a very understandable mistake - look how similar the icons are:
- The strange thing is that the wait block in infrared mode sometimes did seem to to be able to receive readings from the ultrasound sensor, so the program sometimes seemed to work, at least partially - this is why it took so long to spot the problem. This problem could have been avoided if the education software did not make available the infrared sensor mode by default, for this sensor is not even included in the kit. It should perhaps have been made available as an add-on, like the ultrasound block is available as an add-on for the home version of the EV3 software. The moral of the story: tell your students to be very careful not to confuse the wait block's ultrasound sensor mode with the infrared sensor mode, and if it seems that the ultrasound sensors are not working properly then check that the correct mode was used.
- Several students have complained while using the EV3 software that their computer keyboards have stopped working. I can confirm the problem, which goes away if the computers are restarted, but I have not found any confirmation on the internet that anyone else has experienced this problem. Am I imagining it?
- On two occasions the intelligent brick froze - it became impossible even to turn it off in the usual way. To reset a frozen brick:
- Hold down the Back, Center, and Left buttons on the EV3 Brick.
- When the screen goes blank, release the Back button.
- When the screen says “Starting,” release the Center and Left buttons.
- Resetting the EV3 Brick does not delete existing files and projects from previous sessions in the EV3 Brick memory. Files and projects from the existing session will be lost. If resetting doesn't work then you can always unplug the battery.
- Although I have read that you must hold down the Back, Centre and Left buttons it seems to me that holding down the Back button and then just the Centre button (for several seconds) is sufficient. Do you agree?