Debbie Herridge unwraps the mummy of ‘topic work’ and discovers a wealth of practical science experiments within...

Herridge, Deborah

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66Igrew up teaching ‘topics’. In fact I grew upteaching the ‘integrated day’ where everysubject was rammed into ‘the topic’ whetherit fitted or not and ‘doing the Egyptians’ wasthe time to teach pyramids in shape, rivers ingeography and forces in science. Why forces?Because they needed to drag the stones tomake the pyramids, didn’t they!Hmm...tenuous? I’ve come up with one or two scienceinvestigations that will enhance your Egyptianstopic but still maintain the integrity of thescience. Remember – we don’t have to teachsomething that fits into a QCA unit to beteaching science well, any investigation thatdevelops a science skill is worthwhile, so enjoyinvestigating.LESSON 1Mummify a tomato!Mummies are fascinating relics of theEgyptian civilization and a greatplace to startinvestigating – not with a real body, of course,but with a tomato!The ancient Egyptians believed that thebody of a dead person needed to be preservedin order that the spirit of the deceased couldlive on in the afterlife. To begin with, Egyptiansprobably noticed that bodies buried in the dry,hot sand of the desert tended to dry outnaturally and become mummified. As theircivilisation became more developed,complicated rituals and processes evolved toproduce more sophisticated mummies.The first step in mummification is to get ridof the wet and gooey stuff; dry materials areless likely to rot and decay than damp ones.Unfortunately for budding embalmers,tomatoes, like us, contain a huge amount ofwater. The drier we can get our tomato the lesslikely it will rot.Step 2 - Stop the rotChildren can test this idea by sealing slices ofbread in two separate Ziploc bags - or closedpop bottles. They’ll also need to place a 1cmlayer of dry sand in one container and a similarlayer of damp sand in the other. After a fewdays, observe which conditions are best formould to grow on the bread. Imagine this onyour mummy. Yuck!Step 3 - Watch and learn Before you start – observe your tomato reallycarefully. What does it feel like, smell like, whatcolours can you see, what about the texture ofthe skin? Keep an un-mummified tomato as acontrol to provide a comparison.To dry out our tomato we need to make asmall incision in the fruit and scoop out theseeds inside. You can throw these inside bitsaway. The Egyptians did the same with theinternal organs. They kept the heart, whichthey placed inside the mummy, and the lungs,liver, stomach and guts which were kept insidecanopic jars for protection. The body cavity was then washed with wine;the alcohol was supposed to kill germs. Childrencan carefully rub their tomato inside and out witha dilute anti bacterial solution like ‘Milton’ then drythe excess with kitchen paper.Now weigh your mummy. This is the pre-mummification weight with water.Next we need to pack the body with a type ofnaturally occurring salt called natron. We can’teasily get real natron, but we can make it from amixture of table salt and bicarbonate of soda;epsom salts work well too. More able children canexplore the different combinations and proportionsof chemicals that work best in mummification, but equal quantities of each is a good mix to start with.Pack your tomato cavity with your natron andthen place it in a container so it is completelycovered with the salt and bicarbonate of soda mix.Check its progress every few days; you may needto replenish the natron to keep it dry.The Egyptian embalmers had to wait 70 daysto complete their mummy, yours should be readyDebbie Herridge unwraps the mummy of‘topic work’ and discovers a wealth ofpractical science experiments within... schemePyramidEqyptian Science qx  7/8/09  16:07  Page 1in a couple of weeks. What does it look like now?How has the colour changed, the texture? Weighyour tomato again – the difference is the weight ofthe water that has now been removed. If you want,now you can make and decorate a sarcophagus foryour mummified fruit!Step 4 - A lot of hot airDespite this painstaking procedure, it wasevaporation, caused by the hot and dry Egyptianair, that helped the mummification process themost. And we can investigate this in the classroomusing salt water.Ask the children to mix up a saturated solutionof salt and water – they should reach the pointwhere no more salt crystals will dissolve into thewater. Now use the solution to paint a simpleEgyptian symbol, such as an ankh, on a piece ofblack card; you might need to go over it once or51Eqyptian Science qx  7/8/09  16:08  Page 2SCIENCEtwice to apply enough salt water. Leave it todry – what happens? You’ll end up with a shimmering whiteimage on the black card where the water hasevaporated leaving the salt behind. Where hasthe water gone? Can the children investigateways to speed the evaporation process up? LESSON 2The gift of the NileThe Greek historian, Herodotus, called Egypt‘the gift of the Nile’, meaning simply thatwithout the river there would be no Egypt.Rainfall in Egypt averages around 4cm a year sowater is extremely valuable. Only the tiny stripof land by the river could be cultivated and theannual inundation of the Nile was hugelysignificant for the ancient Egyptians. We canuse this information as a context for aninvestigation.Ask the children to imagine they areancient Egyptian farmers. Use some fastgerminating seeds such as radish, beans or alettuce selection (all Egyptian crops) toinvestigate the least amount of water neededfor seeds to germinate. Put dry sand in fivecontainers to about 1cm deep. Count out orweigh equal amounts of seed and scatter overthe sand. Add no water to the first dish, 20cm3to the second, 40cm3 to the third and so on.Check every day for signs of growth. Can seedsgerminate with very little water? How did theEgyptian farmers overcome the problems oflack of water in the fields? It wasn’t just water that restricted farming;the four month inundation of the Nile coveredthe valley floor with fertile silt which madefarming along the river bank and nearby plainseasy in ancient times. Farming in wet, fertile soilis fine, but what about growing plants in lesspromising soils? Ask the children to devise atest to illustrate the least fertile to most fertilegrowing conditions – from 100% sand to100% garden compost and points in between.Where do the plants grow best?LESSON 3Here comes the sunThe ancient Egyptians measured time and werethe first people to divide both the night andday into 12 equal parts, which gave us the 24hour day. They had several ways of using theshadows cast by the Sun to tell the time andchildren can investigate how they did this.Find a sunny point in the playground andplant a PE/rounders pole there. Note theposition of the Sun and draw round theshadow of the stick every hour on the hour.How do the shadows change? Is it the samethe next day? Challenge more able children tomake a portable sundial. What would theyneed to know to tell the time using theirsundial in locations other than the originalschool yard position?Ancient Egyptian religion said that the Sungod Ra travelled across the sky in the daytimeand was swallowed by the goddess Nut atnight and reborn from her at dawn. Can thechildren describe and compare our currentscientific ideas of why the Sun appears to moveacross the sky with those of the Egyptians?  Activities galoreThese are only a few ideas, but there are somany ways we can bring science into a topicon Ancient Egypt: thinkMythbusterWHAT DO THE PROPOSALS FOR THE NEWPRIMARY CURRICULUM REALLY MEAN FOR SCIENCE? MYTHIt’s not a core subject; there are no SATs so I don’tneed to teach science any more REALITYAll subjects will continue to be taught and sciencecontinues to be central to children’s learningMYTHEverything needs to be topic basedREALITYThe intention is to make relevant and meaningfulconnections across subjects where appropriateMYTHWe can only link Science with D&TREALITY D&T connections are useful but teachers cancontinue to link science with all of the othersubjects where appropriateMYTHWe don’t have to do science enquiry any moreREALITYScience enquiry is more important than ever aschildren are now expected to learn by ‘doing’about comparing and contrasting modern andancient Egyptian food and diet, which was‘better’; was gritty bread better or worse fordental health than a modern diet of sugary food.For an investigation of rocks and soils, think aboutwhy Egyptian structures like the pyramids andSphinx remained and others, like the adobeworkers dwellings, have not? Why did theEgyptians wear white clothes? Are white clothescooler than black? How can we find out?There are endless investigations to enjoy inyour Egyptian topic and whatever you decide todo it’s the process of finding out that matters. 53Eqyptian Science qx  7/8/09  16:11  Page 4

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