Which Practical(s) for AS and A2 Levels give you the most trouble?

Discussion in 'Science Technicians - General Discussion' started by GeorgetheScienceTech, Sep 12, 2019.

  1. I'd be interested to know which Practical(s) for AS and A2 Levels give you the most trouble? That way we could all work together and give each other tips to improve the quality of the practicals delivered.:)
    CrowyTech likes this.
  2. Any that cause lots of washing up.

    I will keep a note and let you know at the end of the year :D
  3. JFKtech

    JFKtech and then there were two - now JFK Techs :)

    The ones they order with 3 days notice, with a weekend in the middle, needing chemicals we don't have in stock !

    More seriously - Hill reaction is always hit and miss. Students don't often get good results with DNA electrophoresis, but I think that's mainly because the teachers try to fit it in to too short a lesson. Root tip mitosis usually one group out of the class can see something useful, likewise gram staining.

    Can you tell I'm not a biologist ?! I'm sure there are more that I've forgotten about. Chemistry on the other hand I can usually rewrite to make it work, and physics practicals tend to behave themselves.
  4. This is just one huge advantage of a microscope camera, linked to the projector. Allows everyone to view the successful slide at the same time, preventing queuing to all have a look down one microscope.
    GeorgetheScienceTech and JFKtech like this.
  5. JFKtech

    JFKtech and then there were two - now JFK Techs :)

    Oh I do, but the teachers still get stroppy because most of them 'didn't work' (and obviously that's my fault :rolleyes:)
    Jaytee and GeorgetheScienceTech like this.
  6. I have set of prepared slides for that eventuality.
  7. Yes I did get the impression that you weren't a Biologist JFTech.:D Yes when something doesn't work it's the Technician who gets it in the neck! There is a way of avoiding this - perform and trial the practical before the actual practical takes place and show the Teacher the results. That way you won't be blamed for the failure. Finally the Hill Reaction can be problematic but in my experience if a good Chloroplast solution is prepared and the DCPIP is not too concentrated (if it's too concentrated you'll be waiting all day for results) good results can be obtained).For the DNA Electrophoresis I'd advise the Teacher to allow the students 20 minutes or so to practice loadind the wells with the Micropipette so that sample is actually loaded on the gels in the real run. It's also good practice to check that the students have turned the power on. :pHope these tips are of use.:)
  8. For the hill reaction, just don't do the method in the AQA handbook.
    GeorgetheScienceTech likes this.
  9. I made modifications to it 5 years ago Paul - and it worked ever since!:):rolleyes:
  10. The teacher prefers the way OCR previously did it with the filters and capillary tubes.
  11. JFKtech

    JFKtech and then there were two - now JFK Techs :)

    My lot do Edexcel SNAB, no capillary tubes involved. If anyone would be willing to share an improved method I'd be very grateful !
  12. For the Hill reaction, we've always used the method given in the "Experimental Biology Manual" by Brown & Creedy (published in 1970/71... the old ones are the best, but the book's falling apart a bit now, and we do omit the part that says to use potassium cyanide ;) Different times.........!) Never not worked for me yet; the key seems to be keeping all the solutions ice-cold - doesn't work too well if stuff warms up a bit.... :)
    Beaker likes this.
  13. The biggest issue is with the exam board themselves lol

    The core practicals are assessed on specific criteria set by the DfE
    They don't mind us changing the practical methods out for ones we know work or even making up extra practicals as long as they still can be considered against the criteria, so where the suggested methods can be improved we do and that's all fine, however....

    The exams have questions based on the core practicals, worth a reasonable number of marks
    Out of necessity the questions will be based on the exam board methods which is where the problems arise

    The method set are fairly awful with vague instructions, concentrations which wouldn't work, instructions in the wrong order etc. etc (which is what necessitates the alterations to different practicals mentioned before)

    So our students are doing practicals one way and learning a second method because when the questions are asked they will be on the textbook methods

    Also speed of sound using a dual trace oscilloscope can do one, I can get it but then it never bloody works as soon as the students get their hands on the oscilloscope
  14. they had the mass, acceleration, velocity one in the exam but done properly as the stacked trolley experiment should be not the way edexcel has it in the books.
  15. Can recommend the Cleapss method for the Hill's reaction. So much better than the AQA one.
    GeorgetheScienceTech likes this.
  16. Janus Green is far superior than Methylene Blue in the Dehydrogenase Required Practical.:);)
    Last edited: Oct 3, 2019
  17. it's DCPIP though.
    GeorgetheScienceTech likes this.
  18. You are right as usual Paul.:)
  19. DMS


    We had the Hill reaction work successfully this week following AQA A level method. However, we had to dilute the DCPIP to 12x the original concentration stated in order to see the colour change.
  20. Agree with above, DNA elecrophoresis is no problem for me to do, but due to shortage of time, students never see results, waste of time & money as all they do is practice putting dyes in wells.
    Maggot practical is my nemesis. I use all the right equipment, but the damn things get everywhere, doesn't help that the pupils empty the tubes & throw them around. I can never find/keep enough woodlice to use instead.
    Plus the kids seem to manage to make the liquid shoot out of the capillary tubing every time & I have to be in lesson to clean & refill,:( again, like you all, it seems to be my fault somehow. It's like the teachers have never actually MET children!