Background knowledge


Bread mould thrives in warm, humid conditions. To encourage bread mould growth for this activity, dampen some bread slices, put them in a plastic bag, and leave the bag in a warm place. Mould should start forming in a few days.


Assessment guidelines


• This activity is intended for informal assessment. • Go through the instructions of this activity with the class and ask them what they observe.


Activity 2 Examine and analyse a photograph of a micro-organism Learner’s Book page 51 Guidelines to implement this activity


• This is an individual activity. • Before learners begin this activity, take a different micrograph and demonstrate how you would go about using the scale to calculate the real size of the organism – you can use the worked example to aid your demonstration.


• Ask learners to write down each measurement as shown in the Learner’s Book Figure 7 from Steps 1 to 4.


Suggested answers • Length of paramecium in photograph = 87 mm 


• Length of line that represents 25 micrometres = 10 mm  • Paramecium length divided by length of scale =  


• Multiply scale length by this factor = micrometre size = real size of the paramecium.  25 μm × 8,7 = 217,5 μm


Assessment guidelines


• This activity is intended for informal assessment. • Write the suggested answer protocol on the board and ask learners to swap their workbooks with a partner to mark them and allocate learners a mark out of 4.


Remediation/Remedial activity


Give learners a different micrograph with a different organism so they can practise calculating its real size.


48


(1) (1)


  = 8,7 factor  (1) (1) Total: 4 marks


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