FSE 10 Teachers activity [PDF File, 3.0 MB] - Centre for Learning ...

FSE10forensic entomologyTeachers: Activity InformationActivity 7 – Accumulated heatFSE04Analogy: Ask students to think about the steps inbaking a cake. The oven must be set at a certaintemperature--and the cake must remain in the ovenfor a certain length of time--in order for it to bakeproperly. A cake placed in a cold oven won’t bake nomatter how long it remains there.Ask students how the requirements for baking a cakemight be similar to the needs of growing organisms.See if they can develop the analogy to explain thatit takes a certain amount of heat, accumulated overtime, in order for some organisms to grow.Also, just as a cake requires a certain temperature forproper baking, there’s a threshold temperature atwhich organisms begin to grow. This is called the basetemperature or lower threshold temperature.The base or threshold temperature varies betweentypes of organism, for example plants and animalsand also between species.Insects are cold blooded or Poikilothermic and arehence reliant on the environmental temperature.In this activity the lower threshold temperature isconsidered to be 10 o C.Suggested Activity:Measure the Maximum and Minimum Air TemperatureEach Day.• This is an extension of Activity 3: MonitoringTemperature, Table 2.• Transfer the temperature data from Table 2 toTable 5.• Calculate the Amount of Heat Accumulated eachday.• Use as the lower threshold temperature 10 o C.Note:ööSubtract the base temperature from theaverage daily temperature. These dailyunits of heat are called “Growing DegreeDays”.Particular insects have different temperature baseshowever 10 o C will be the designated the artificiallower threshold temperature.If the daily average temperatures are > 10 o C, thenthe degree-days for that day are equal to the Avetemperature subtract 10 o C.If the daily max and min temperatures are < than 10 o C,then the degree days for that day are = 0.If the average max and min temperatures are greaterthan 40 o C (upper temperature threshold), then thedegree-days for that day are 0.13