Mini-task: Temperature Q 1. Getting a feel for different temperatures Temperatures are usually measured in degrees Celsius ( C). The scale below gives you an idea of what some temperatures mean: Using your own experience and the guidelines in the chart above, match the temperatures from the box on the right with the situations listed below: The first one has been done for you. Situation: Temperature Temperature in my office 5 C Temperature in my fridge 39 C Oven temperature 93 C Temperature of water in a kettle after it has 31 C boiled My son s temperature when he s feeling ill -15 C Outdoor temperature on a very hot day 21 C Temperature in my freezer 24 C Water temperature at my local swimming pool 200 C Page 1 of 8
Q 2. Different temperature gauges In your everyday and working life, you will come across temperatures being shown on a variety of different gauges (dials and thermometers). Can you label each of the gauges shown below with the suggestions from the box? body thermometer radiator dial oven dial meat thermometer weather thermometer Gauge A: Gauge B: Gauge C: Gauge D: Gauge E: Which of the above doesn t show a temperature in C? Think about temperatures you come across in your everyday or working life. What temperature gauges do you have around you? What sort of temperature ranges do they typically show? Page 2 of 8
3. Reading gauges There may be times when you need to: read a temperature from a gauge or set a gauge to a particular temperature. Sometimes the scale on the gauge you are using may not have all the numbers actually labelled. By looking at the points that are labelled, you can work out where the numbers in between (that are not labelled) would go. Example: On this oven dial, the scale shows the numbers 60, 80, 100, 120, etc but not the numbers in between. This dial is showing a temperature somewhere between 160 and 180 C. You can visualise in your mind where intermediate numbers will go: halfway between 160 and 180 will be 170; halfway between 170 and 180 is 175 C. So the dial in this example is showing about 175 C. Q 3(a) What temperatures do each of these dials and thermometers show? Gauge A: Page 3 of 8
Gauge B: Gauge C: Q 3(b) Mark the temperature shown onto these dials: Gauge A: Mark 200 C onto this oven dial Gauge B: Gauge C: Mark 7 C onto this thermometer Mark 23 C onto this thermometer Page 4 of 8
Gauge D: Mark 170 C onto this oven dial 4. Temperature and food safety In contexts that involve handling food, temperatures are very important for making sure that the food is safe. Microorganisms, many of which can cause illness, grow at temperatures between about 8 C and 63 C. The temperatures within this range are seen as a possible danger zone for food. Highlight this food danger zone on the scale below. Below are some other key temperatures for food safety: To kill bacteria, they need to be subjected to a temperature of 77 C or more. So: dishes washed in a dishwasher should be at this temperature or higher. Hot food should be kept at over 63 C. Chilled food should be kept at below about 8 C. Refrigerated stores should be kept at temperatures between 0 C and 5 C. Frozen food should be kept at below -15 C. Q 4(a) Decide which temperature range from the list above each of these shaded areas shows: The first one has been done for you as an example: (i) This shows the temperature range: 77 C or more (ii) (iii) Page 5 of 8
(iv) Q 4(b) Frozen foods As was shown in the diagram in section 1, 0 C is freezing point of water. In other words, at temperatures below 0 C, water turns to ice. So, when the temperature outside falls below freezing point, the weather gets icy. Often we refer to: temperatures of 0 C or above as above zero, and temperatures of less than 0 C as below zero. Temperatures on either side of freezing point are shown on the gauge below: The numbers below freezing are described using negative numbers : minus 1 (-1), minus 2 (-2) etc. Notice that with temperatures below zero, as the numbers seem to get bigger, the temperature gets colder. So -8 C is colder than -2 C. As was shown in the list of key temperatures above, frozen food should be kept at a temperature of -15 C or below. A typical fridge is usually at less than 5 C. If the temperature of the fridge falls below 0 C, the fridge will start to ice up. A freezer is usually kept at a temperature of around -15 C. Page 6 of 8
Mini task: Temperature Answer Sheet Q 1. Situation: Temperature Temperature in my office 21 C Temperature in my fridge 5 C Oven temperature 200 C Temperature of water in a kettle after it has 93 C boiled My son s temperature when he s feeling ill 39 C Outdoor temperature on a very hot day 31 C Temperature in my freezer -15 C Water temperature at my local swimming pool 24 C Q 2. Gauge A Oven dial (180 C) Gauge B Meat thermometer (72 C) Gauge C Body thermometer (37 C) Gauge D Weather thermometer (27 C) Gauge E Radiator dial (not a temperature in C) Q 3(a) Gauge A 190 C Gauge B 36 C Gauge C 26 C Q 3(b) Gauge A Oven dial showing 200 C Gauge B Thermometer showing 7 C Page 7 of 8
Gauge C Thermometer showing 23 C Gauge D Oven dial showing 170 C Q 4(a) (i) 77 C or more (ii) Between 0 and 5 C (iii) Less than 8 C (iv) More than 63 C)) Page 8 of 8