Time permitting, instead of telling the pupils what they should look for as evidence of differing deaths of the holly leaf-miner, allow the pupils to observe several mined leaves and to write down what they actually see. Leaves can be collected by the pupils or prior to the lesson. Use a hand lens to observe leaves and record any details observed. Make sure that both sides of the leaves are checked. Demonstrate how to open a mine safely and without damaging the contents by cutting around the mine and gently pulling the two epidermises apart. Again the pupils should record what they find.
At this point the keys (Text ID key and Photo ID key) may be introduced. By comparing their observed information with information in the identification key, groups can tell the class how their miner died (if at all).
Methods of sampling information from books and the internet can be discussed, leading to agreed methods for sampling holly trees. Sampling methods will have been taught at KS3 so this may be an ideal opportunity for pupils to devise their own method to sample a holly tree. Differing sampling methods can be presented, with advantages and disadvantages of each method discussed.
- To sample 600 leaves; split class into 6 groups.
- Each group should sample 10 randomly chosen branches.
- For each branch ignore the first few young leaves and record the number of leaves with and without mines for the next 10 leaves along the branch.
- Cut off the holly leaves that have mines and place them in a plastic bag.
- Take notes of any problems or changes that had to be made during the practical.
Caution should be exercised when collecting holly leaves. Pupils should wear gloves. Consider eye protection.