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Energy flows in food chains and efficiency in food production - how to make interactive?

Discussion in 'Science' started by ferrisbueller, Feb 16, 2012.

  1. ferrisbueller

    ferrisbueller New commenter

    Before I start, yes, I do have my own ideas, and no, I'm not expecting a full singing and dancing lesson plan. I just need some ideas to make this topic a bit more interesting.
    I currently have a quite good ppt on the subject (if I don't say so myself!!), but very little for the students to do, apart from work out % of energy 'wasted', and discussing where energy may go if not into the biomass of the consuming animal.
    So, my plea is for any good demos, short practicals, or resource to make this subject a bit more interactive, rather than telling students things and asking them to fill in a worksheet.
    Thanks in advance.
    Love, Ferris

  2. pink_reindeer

    pink_reindeer Occasional commenter

    How about some sort of kinaesthetic activity? Not really sure how it would work, but you could get students to wear name tags (grass, rabbit, fox or something) and get them to hold cards with words on them to represent why the organism would use energy (eating, running away from predators, moving to find their food) or maybe even just cards that represent energy. The sun would give all the cards to the pupils representing grass, the pupils representing grass would use some of the energy whilst growing and photosynthesising, pass on some of the cards to the rabbits, who would use some of the energy for various activities, passing some on to the fox. Sorry it's a bit waffly, and I have no idea if it would work. I get a lot of help from these forums so wanted to try (being the key word!!) to help!!
  3. ferrisbueller

    ferrisbueller New commenter

    Thanks pink reindeer, and good luck with your interview. I would employ you just for your enthusiasm alone! [​IMG]
  4. pink_reindeer

    pink_reindeer Occasional commenter

    Awww, thanks. That's such a nice thing to say!! I love your username by the way!!
  5. sadscientist

    sadscientist Senior commenter

    You could use a lottery win analogy which goes something like -
    Lucky me wins £1000 on the Lottery, lose £500 when I get mugged (or whatever), spend £400 on (whatever) and give £100 to my favourite pupil (whoever).
    Selected pupil uses the £100 in same proportions and gives £10 to best friend.
    It ends up of course with someone getting a penny, not enough to live on unless they get pennies from lots of people.
    (I make a shaggy dog story out of this, you can alter to suit your class and start with more money to make the food chain longer!)
    Yoy can talk about what the parts of the analogy represent and how it is similar/different to energy in food chains.

    Compassion in World Farming (you'll have to Google) have some good and quite balanced stuff on energy in food production, some of it is now a bit dated as laws have changed, but you can dowload or get DVDs.

  6. BelleDuJour

    BelleDuJour Star commenter

    That works even better if you use a ball of string and get them to connect with each other.................kind of a living food web!
    Just get laminiated pictures and get them pinned or stuck onto the students (including sun).
    Give the sun the ball of string and pass it on to any green plants and so on to make a big, messy food web. It's really fun. You can try to 'detangle' the web by introducing a disease that wipes out one organism. Hard to describe but does wrork well in practice.
  7. ok, so what i did when i did this with my class was get some beakers of water, one massive beaker of green water, one smaller one of yellow water and one of red water. the green one symbolising a field of lettuces, the yellow one symoblising energy from the sun and the red one a rabbit. I also had several empty beakers smaller than all the rest, and lots of sticky labels

    so i demoed the energy flow, explaining that the energy stored in the field of lettuces was the contents of the beaker containing green water, i added some of the yellow water and explained that was the energy from the sun going into the lettuces, then along comes roger and some of the green water was poured in to top him up, and then we talked about where that energy in roger went, and poured some of his energy out and labelled a number of beakers.

    then we put it into numerical terms.... and that was when the fun started :)

    it is a good activity for AfL, you could give out some examples and get them to calculate the energy available at the next level and % efficiency, and expalin why food chains are limited in length and get them to peer assess answers etc etc.

  8. I went down the modelling route for an interview lesson on this topic once. I like a bit of drama in the classroom and used a large box of plastic balls that was passed down a four-stage food chain, with energy being lost at each stage. what could possibly go wrong I thought??... we can talk about respiration, excretion, throwing energy out as we go. Fun, kinaesthtic, memorable, etc. etc. Alas, I hadn't factored in the type of children I might possibly be teaching. The most dull yr 10.2 ever. The couldn't have been less receptive and were so passive they didn't even try to misbehave. My lesson died on it's feet. And no, I wasn't offered the job!
  9. I have just covered this. Food chains of different lengths ( each trophic level being 10m) and students running between them with plastic cups with holes in them(filled with water) and filling up a measuring cylinder at the end of the food chain!
    Fantastic activity for a great lesson!
  10. This is the jist of what I've done in the past - you can get the kids outside, have a nice deep tray filled with water for the sun, then you could use practically any other container for producers & consumers. Measuring cylinder is a good idea, previously I've just used trays and you can make a rough comparison at the end.
  11. blazer

    blazer Star commenter

    I remember once (actually a few times) giving all the kids i the room a picture of an organism. I did it so the front row had the plants the second row the primary consumers etc. they had information about what ate what etc.

    Then I gave balls of wool to the kids in the front row and they gave strands to the things that ate them, then strands gotr pased onto the third tiwer etc. By the time they had finished the whole room was one big web (literally).

    Next step (with bright groups) was to remove some of the strands and then discus what would happen.
  12. flimsynight

    flimsynight New commenter

    Short demo but worked for me.... 100 smarties in a cup (plant). Give 10 to a student with another cup (herbivore). Throw the 90 left straight in the bin. The kids went wild! Then herbivore passes one smartie on to a carnivore, the other 9 go in the bin, more shouting and complaining from the kids. Shows energy transfer in a basic way but produced such a reaction that the kids won't forget it!!

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