|Lesson Title: Looking at a Snake||Unit: Classification (Extension)|
|Aim: To show how the features of an animal relate to its lifestyle, habitat, etc., and introduce some basic evolutionary ideas if desired.|
|Note: This is an optional lesson, to be added if it is felt that it will reinforce the ideas presented in the unit. Obviously a suitable snake needs to be available for study; see safety considerations below. The lesson plan below relates to a corn snake (Elephas guttata), but can easily be adapted to most of the commonly kept snakes, and to other (preferably unfamiliar) animals if a snake is not available. Snakes with abnormal coloration (e.g. "snow corns") may not be suitable.|
|Key Words: Egg-laying (Oviparous), "warm blooded" (Homeothermic), "cold blooded" (Poikilothermic), Shedding|
|Introduction: Pupils should be warned in the previous lesson that the next lesson will involve a live snake, and positioned so that anyone exhibiting a genuine phobic reaction can leave the room easily. In rooms with a single entrance it may be advisable to have the snake in an opaque container (such as a vivarium covered with a box) away from the door before pupils enter the room. Take registers etc. before the snake is introduced.|
|Safety: Care should be taken to choose a snake that is "well behaved" when handled. Larger male corn snakes seem to be especially suitable, females are generally less willing to be handled. The snake should be fed 2-3 days before the lesson. A cloth and disinfectant should be available, in case the snake voids during handling. Check that the snake is not shedding or otherwise likely to be irritable. Some alcohol swabs should be available, or a bottle of alcohol and some cotton wool; if anyone is bitten the wound should be swabbed immediately, if the snake is unwilling to let go the alcohol will drive it away. Use a room that has a sink/wash basin, and provide antiseptic soap; snakes and other reptiles can carry salmonella, so anyone handling the snake must wash afterwards. The teacher MUST be familiar with handling and controlling the snake used for the lesson! Venomous snakes must NOT be used, even those allegedly harmless to humans!|
Make sure that any tutors etc. present are aware that the snake will be used, and are not phobic! Students may need more prompting in all sections
See detailed lesson plan below
Students should need less prompting throughout
|H/W: Write about what it would be like to be a snake.||H/W: Write about the snake's adaptations to its lifestyle.||H/W: As core.|
Citizenship: Wider awareness of environmental issues, e.g. snakes unjustly persecuted
when they were in fact eating pests. The "Simpsons" episode "Whacking
Day" has been shown on British TV, and shows how violent such
persecution can be; snake "culls" of this type are common in parts of
Responsibility for keeping pets and handling them carefully.
OHP Far Side cartoon "God Makes The Snake" (Optional)
OHP Snake skeleton and basic anatomy (Grolier encyclopaedia)
OHP Photo of snake, size of jaw when dislocated drawn onto the picture.
OHP Jaw diagram (Grolier)
OHP Constriction (Grolier - may not be suitable for some groups)
Worksheet: Picture of snake body & scales (Biodidac)
Worksheet: Picture of snake mouth open showing teeth, trachea, etc. (Biodidac)
Video - The Trials of Life (set to correct place as below)
Vivarium, lamp, etc.
For extended lesson (measurement)
Detailed lesson plan
Throughout the lesson it is likely that pupils will have questions related to the snake's anatomy, behaviour, mating habits, diet, etc. If possible they should be answered as they come up, if it will not disrupt the lesson too much. A common question is "how does it go to the lavatory?", since there is no obvious "bottom"; point out the vent and explain that wastes are released from an opening normally covered by scales. For higher ability explain that this corresponds to the position of the pelvis in limbed vertebrates.