Lesson Notes
Lesson Notes
Unit Title:
Monitoring and sensing
Target age group:
9-10
Lesson Title:
Carrying out our own experiment
Lesson Number:
3 (of 3)
Lesson Outcomes
After completing this lesson, most children will be able to:
understand that a device attached to a computer can take readings of conditions such as light intensity,
temperature and sound levels.
understand that a sensing device attached to a computer can take readings of conditions such as light
intensity, temperature and sound levels.
understand that sensors have an important role to play in a large number of commonly used devices.
use a simulation to select and set sensors to protect a valuable painting called Red Mist.
Lesson Starter
Ask your the children to consider a museum. Where do they think the museum might use sensors and for
what purposes?
The main activity for this lesson is a simulation. The children will take the role of the Head of Security for a
big museum. The museum is exhibiting a very valuable painting called Red Mist. They will have to protect it
against theft and environmental damage.
Explain that delicate, old objects, such as paintings, fabrics and books are often kept in controlled
environmental conditions to help preserve them. This usually means keeping the temperature and humidity
within particular ranges. The values used in the simulation, 40-60% relative humidity and 18-24 degrees
Celsius, are appropriate for the preservation of oil and acrylic paintings. Items may be further protected by
keeping the lighting to a minimum. This could be used as a discussion point. Ask your the children what
happens to brightly coloured fabric such as curtains or clothing when these are displayed in a shop window
and exposed to lots of bright sunlight over a period of time. Most fabrics would fade.
Briefly discuss burglar alarm systems, using this opportunity to review some of what has been covered in
previous lessons. What kinds of sensors might be used in a burglar alarm system (movement sensors, contact
switches, vibration sensors, pressure pads, sound sensors, light sensors)? How might a burglar try to avoid
being detected by these different sensors? How should you design your security system to deal with a wily
burglar (a range of detection sensors, not just one type, as well as other measures, such as sturdy doors and
locks, security guards, CCTV)?
To complete the simulation successfully, the children must choose the most appropriate sensors and set them
up correctly. They will know that they have been successful in each of the two sections when the notorious
cat burglar Ruby Grabbit is captured trying to steal the painting. They should record the sensors that
protected the painting and the settings that they used.
After completing the simulation there is a worksheet for the children to complete.
Cross Curricular Links
Major: Science KS2: SC1 Scientific Enquiry - 2f datalogging ; SC3 Materials and Properties - 2b
temperature sensors ; SC4 Physical Processes - 3f sensors
Minor: None
Main Activities
General (including Intermediate)
Red Mist is an activity to help the children understand that there are a wide range of sensors available that
can be connected to a computer. A particular sensor must be carefully chosen for the job that it does because
each type of sensor has a specific purpose, such as measuring light or temperature.
The children begin by acting as Head of Security for a museum exhibiting the very valuable painting Red Mist.
They have to choose the most appropriate sensors to use for environmental and security monitoring. They
can read information about each sensor and are allowed to progress only when they have selected
temperature, humidity, movement and pressure sensors as their four allowed inputs.
If the children click on the humidity sensor they see a short explanation of humidity, using the contrast
between a steamy jungle and a dry desert. This links to a humidity-time graph.
Note: While the program is guiding the children towards a particular choice of sensors, a case could be made
for using a different selection. This could form the basis for a discussion of the relative merits of different
sensors within a security or environmental control context. When might a sound sensor be more useful than a
pressure pad (in situations where the expected method of entry involves tunnelling or breaking through a
window or heavy door)? Why was the light sensor not particularly useful to the museum (light from outside
the building could trigger false alarms)? Under what conditions might a light sensor be more useful (in a room
with no windows or heavy curtains/shutters)? The heart-rate sensor is the only one that is entirely
inappropriate in this particular context.
An incorrect choice by the children will result in either a false alarm or the painting being stolen. The children
are told what happened as a result of their choice, and this will give them a clue as to either which sensor
was missing or which one was surplus to requirements. They must then adjust their choice.
When the notorious cat burglar, Ruby Grabbit, triggers the museum's alarms and is captured, the children will
know they have made the most appropriate choice of sensors. They then progress to the second section,
where they have to adjust the sensor settings. They can set the desired temperature (18 to 24 degrees) and
humidity (40-60%) ranges and arbitrary sensitivity values for the pressure pad and movement sensors.
More able students may decide to set the temperature, for example, to a narrower range (say 19-23 degrees)
to give a safety margin. However, if they choose a margin that the program considers too narrow, they will
trigger a false alarm. The children can use trial and refinement to discover what the program considers a
suitable range.
The information section on the pressure pad includes an explanation of sensitivity. They will see that if the
pressure pad is too sensitive then an insect landing can trigger it. If it is too insensitive, a burglar could walk
on it undetected.
If, when the children test their solution, the security sensors are too insensitive, they will not detect the
presence of the recently escaped Ruby, and the painting is stolen. If the pads are too sensitive, a false alarm
results. The children are again expected to use trial and refinement to discover what the appropriate settings
are. They should be encouraged to record what they did and the settings they chose.
The simulation is complete when the children have made appropriate settings and Ruby is once more safely in
custody. The children should then open and complete the (differentiated) worksheet. (All of the children
complete the same simulation.)
Advanced
The advanced-level worksheet has more open-ended questions and expects the children to be able to do
more complex interpretation of a light-intensity vs time graph. These the children would be expected to be
able to discuss the pros and cons of a computer-based security system as opposed to using more security
guards, in greater depth.
Basic
The basic-level worksheets ask questions that are more structured and direct. They only cover elementary
graph analysis.
Plenary
Which sensors were used to protect the painting? Why were these sensors important? Do the children agree
that they were the most important of the sensors available, or do they think that there were better
alternatives? Are there other sensors/devices that they would have liked to use if they had been available for example a grid of invisible infra-red beams to detect anyone or anything moving in the gallery, as in some
films? Why do the children think these were not available (cost, complexity)?
Consider the cost and complexity of a burglar alarm system as against the value of the item(s) being
protected - for example protecting Fort Knox, as compared with a domestic burglar alarm.
This discussion could be widened to consider other monitoring and control applications - for example,
environmental control in an office, where wider operating ranges might be acceptable and you are likely to
find relatively few sensors. Or consider the control of a nuclear power station or a BP Gas terminal, where
safety concerns are paramount and there are lots of sensors in many different places, measuring a range of
conditions, with backup sensors in case of failure.
Consider the shortcomings of alarm systems - possibly creating a false sense of security, forgetting to turn
the system on, false alarms, installation and maintenance costs, people not always responding when they
hear alarms.
Follow-up opportunities
The children could go around different parts of the school, making a list of all the devices they can find
that incorporate sensors.
Curriculum References
National Curriculum 2000 for Information and Communication Technology: KS2 - 1a, 5c
QCA Scheme of Work for Primary ICT: Unit 5F Monitoring environmental conditions and changes