Living things & the processes of life - The processes of life - The Human body & Reproduction - G17 - LT-D2.2

1. The children will be full of information about their own teeth and there are several story books e.g. Ginn Level 6 - The Wobbly Tooth which could be used to introduce the topic. Sets of commercial plastic teeth can be expensive -a possible alternative source could be a local dentist or dental laboratory who may be able to supply a plaster cast of teeth. Be aware of hygiene factors here! Make sure the children to wash their hands before attempting this and it might be more pleasant all round if it is done before lunch! Worksheet D24a (G) ‘My Teeth’ can be used to identify and draw the different types of teeth . Worksheet D24b (G) is a dental diagram and can be used to show the position of the different types of teeth in your mouth and possibly to record which teeth the children have. Worksheet D24d (G) shows the main parts of a tooth. The local dental hygienist can supply leaflets and advice on care of teeth and data on decay and fluoridation in your area. The children could carry out surveys on their own and other classes about frequency of teeth cleaning and amount of dental treatment the children have received. Is there a clear link between how often the children clean their teeth and the number of fillings they have? How could the children improve their own dental care? Can they make a poster to encourage younger children to look after their teeth?
Teeth Incisors - sharp edged and positioned across the front of the mouth for biting. Top teeth should overlap the bottom ones. These act a bit like nail clippers ! Canines - most obvious in dogs! Pointed teeth at each end of the row of incisors. These act like a paper punch. Premolars - lying next to the canines and having a ‘double peak’ to help crush the food a bit like a garlic press. Molars - Big ridged teeth at the back with very deep roots, crush and grind food like a pestle and mortar.
Teeth evolved from the scales of cartilaginous fish and are adapted to the lifestyle of the animal. Our teeth have central pulp cavity which contains soft tissue, nerves and blood vessels. This is surrounded by a layer of harder material called dentine and this in turn is capped with a layer of enamel which is the hardest material in the body. Enamel is extremely resistant to wear and tear and to decay. The root of the tooth is embedded in the jawbone to give it a solid foundation. Milk teeth do not have roots and so fall out easily when the adult tooth pushes up from below.
Shark’s teeth are used to catch prey and tear flesh. Nurse sharks cope by moulting their teeth and growing a new set every 8 days!	An interesting extension exercise would be to find out how many missing teeth each child has and collect the information to make a bar chart. Worksheet D24c (G) is a template which can be used and adjusted for this.
2. To help the children to think of where the food goes to remind them of feeling full after a big meal - where do they feel that sensation? Perhaps they have swallowed something rather large at some time - maybe not having chewed it properly - or maybe they have swallowed something too hot - these are times when we feel food travelling down our gullet. Worksheet D24e (G) can be used to learn the names of the organs.
Digestion Food is chewed into a paste and mixed with saliva in the mouth. The stomach ‘mixes' the paste with acid and other chemicals to break it down more. Into the small intestine where alkali and other chemicals are added to break food down further and dissolve different parts of it. Moving along the small and large intestine the digested food is absorbed into the blood to be moved around the body. Any bits that can’t be used are collected and passed out of the anus.