Biodiversity. How many separate species live on the planet (not known exactly: could be between three and 30 million, with about 750,000 kinds of insect alone)? How do species live together (some in “antagonism”, predator and prey, creatures fighting for the same food; others in a “mutual” relationship, “symbiosis”, where species help each other, pollination, food-digesting bacteria)? How does the chameleon change its colour (not to match its background, a common misconception; it develops coloured pigments to reflect its mood, fear, the temperature, or light)? How do creatures catch their food (claws, teeth, web, venom, pincers, open mouth, tentacles)?

The tongue What exactly is the tongue (a network of muscles, glands and fat, covered in mucous membranes and usually anchored to the floor of the mouth)? What is it used for (tasting, squashing and lubricating food, swallowing, grooming - cats, speech)? Your tongue is important in speech, so sound out phonically letters such as l, r, s, t; notice where your tongue is for each (behind your teeth - l, near or on the roof of your mouth - r, s, t). Think of another creature that catches insects with its tongue (frog). Why do babies put things in their mouth(lips and tongue are particularly sensitive)?

Writing. (a) Pretend you are a biologist studying predators and describe your observation of the chameleon watching and then catching its prey; (b) write a funny caption or speech bubble for the picture (chameleon: “I got this free with my comic”; insect: “Don’t you know that sticking out your tongue is rude?”).

Ted’s talking points

What would happen if you reached across the table and grabbed some food like this chameleon? Would you get a slapped hand? Are “table manners” and “correct” etiquette a good thing?

For. We need a proper code of conduct. Good manners are based on common sense and respect for others. If you eat peas with your knife you might cut yourself; if everybody grabbed food at meals it would be chaos. You let someone go through the door before you to avoid injury, you give up your seat on a bus for a mother with a child to help her. Without good manners life would be brutal, as in the wild. We would be no better than animals.

Against. “Manners” and “etiquette” are forms of snobbery. Who cares whether you eat peas with a fork or a spoon? These are middle-class conventions that get imposed on children, mostly for no good reason. They are also relics of a bygone age, like walking on the right of a woman so your sword arm is free. Just encourage common sense and respect. That will produce good behaviour without any precious and inflexible rules.

Ted Wragg is professor of education at the University of Exeter.