Lethal Lunch Boxes!

as seen on TV!

Kimberley Fenton investigates why her lunch gets hot at school

This is the veranda outside in the sun where the class put their bags(and lunches) for the whole day.


Another winning science fair project.

What were the factors making her school lunch taste so awful?

10 year old Kimberley Fenton demonstrates you are never too young to think like a scientist...

My problem

In the summer (mostly) I have found that the bags on the outside hooks at my school are getting way too hot for too long. People’s sandwiches were going soggy, yogurts turning sour and parents were coming in complaining. I understand that the temperature that bad bacteria grow in is called, ‘The Danger Zone’. Food stored for a long time in the Danger Zone can cause food poisoning. I wanted to find out what was making my lunch go off when I had my bag stored outside the classroom on the hooks.


  • To see how long my lunch box was being kept hot and in the Danger Zone.
  • To find out what was causing the heat.
  • To think of a way to avoid this problem and keep food safe at school.


I used a sensor system called RIGEL which was programmed to act as a thermometer. The thermometer was tested against mercury thermometers and was accurate to 1 degree. I plugged in two temperature sensors and put one in my lunch box and the other outside my bag to measure the air temperature.

Later on I added an infra-red heat sensor as I noticed that when my hand was in the direct sunlight it was the sunlight that had all the heat in it. The final experiments use three sensors:

  • An Infra-red heat sensor outside my school bag
  • A Temperature sensor outside my school bag
  • A second Temperature sensor in my lunchbox

I took readings all day from about 8:30am to around 3:30pm every ten seconds.

The sensors collected about 2,500 readings each day.

I did my experiments in December, February & March as these are the hottest months of the school year.

Once my data collecting was finished for the day, I plugged the sensors into a desktop computer and all the readings were uploaded into Microsoft Excel.

I then used the Chart wizard to display the data in a line graph. I also used Excel to work out the maximum, minimum, and average temperatures.


The food is affected by absorbing infra-red heat energy more than the outside air temperature

  • Maximum Temperature 75oC
  • Minimum Temperature 15oC
  • Average Temperature 30oC

Danger zone for food

I found out that our lunches were being kept in the Danger Zone (between 15 - 45oC) for a few hours a day!

I then needed to know what was causing the heat. So I put, just sticking out of my bag, an infra-red light sensor. Infra-red is a type of heat energy. I noticed that the heat inside my lunchbox followed the Infra-red heat energy better than the outside air measurements.

I found out that it was the direct sun light that was making the heat so intense. The heat from the outside air and the lunchbox sort of follows the pattern that the infra-red makes.

I discovered that while the outside air did warm up the lunch box, it was the infra-red heat energy from being in the direct sunlight that had the greatest affect on the temperature of the lunchbox. My food was in the Danger Zone for quite a few hours.


I noticed that in the summer my school lunch had gotten to a rather high temperature, whereas in the winter, I had never had a problem like this.

Also, now my bag is in a Cloak bay, I can take sandwiches, cake, or even yogurts to school without them getting soggy or sour.

I think this is because my bag is not in direct sunlight, so it is not getting affected by its infra-red heat energy.


My recommendations

  • To take the Lunch boxes inside the classroom instead of leaving it on the hooks outside.
  • You could also put an icepack inside the Lunchbox if you want to keep things like yogurt cold.
  • You also could just keep the whole bag inside or just in the shade.

I have also found that now I have a Cloak bay, I can take yogurts and sandwiches to school without them getting sour or soggy. Although all of these solutions work, my research recommends putting lunches in the shade or, ideally, a Cloak Bay.

Kimberley Fenton, 10


Common Food Poisoning Illnesses



Foods involved

Meat, dairy products and salads.

Generation time

20 minutes at 37OC

Main Symptoms

Fever, headache, aching limbs, abdominal pain, nausea, diarrhoea, and sometimes vomiting.



Foods involved

Meat, diary food, eggs and fish products.

Generation time

30 minutes at 30OC

Main Symptoms

Abdominal pain, severe vomiting, diarrhoea, abdominal cramps, and sometimes collapse.



Foods involved

Meat especially chicken, water and milk.

Generation time

1 hour at 37OC

Main Symptoms

Diarrhoea, abdominal pain, fever, nausea, and vomiting.



Foods involved

Meat, raw milk, seafood, chicken and vegetables etc (eg coleslaw).

Generation time

1 hour at 30OC

Main Symptoms

Acute/mild fever, influenza-like symptoms.



Foods involved

Meat, seafood, water, seafood and raw milk.

Main Symptoms

Under 5 yrs diarrhoea, (sometimes bloody). Over 5yrs abdominal pain (like appendicitis), also fever, joint pain sore throat and rash.

Generation time

1 hour 30 minutes at 37OC



RIGEL - Real-world interactive games and electronics link. A SMARTboard capable interactive real-world game interface, datalogger and proces control system. Suitable for teaching, research and industrial applications.

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