July's Investigation of the Month
Phlubber
Develop observation skills when looking at some interesting ‘solids’
You will need:
- Borax – most pharmacies stock this. (made up into a 5% solution (5ml in 100ml water))
- Talcum powder
- Oil free moisturizer (e.g. baby lotion)
- Glue (PVA)
- Paper cups or beakers
- Teaspoons
- Blu-tack and plasticine
- Cornflour
- Silly putty (can be made with 20ml glue, 20 ml water & 5ml borax solution)
- Tomato ketchup
- Toothpaste
Instructions:
Many pupils may well have met ‘phlubber’ in terms of either the Ghostbusters, or as silly or ‘fart’ putty!! It appears to be a solid, but is really described as a fluid.
Show the ingredients to the pupils & ask what will happen if you mix them all together. (6C)
The pupils can make their own phlubber following this recipe: 1 teaspoon of talcum powder; 10ml moisturizer; 10ml glue; 10ml water, all placed into the cup or beaker. Add 5ml of the borax solution.
Once they have stirred the ingredients the pupils can tip it out and observe its behaviour. Is it as they predicted? To find out more about it, the pupils could investigate what happens when you pull it hard vs gently or trying to bounce it leaving it on the desk, or in the cup. Some comparisons could be made with Blu-tack or plasticine. The ultimate question to answer is whether it is a solid or a liquid. (4D)
Pupils can then explore what happens if you alter the concentration of the borax solution and measure its flow rate. This could be by placing the flubber on a sloping shiny board (whiteboard or laminated card) at a set angle and timing how long to travel a set distance. (SC1). The investigation could be carried out in either year 6 or 7.
Pupils could also look at the effects of stirring on everyday phlubber, e.g. cornflour or silly putty (which stiffen with a force) or tomato ketchup or toothpaste (which flow better with a force). The pupils could theorise why these substances behave in these ways, related to the particle model of the 3 states of matter. (7G)
Safety:
Goggles for the mixing and testing part.
National Curriculum Links in KS2
4D (Solids and Liquids and how they can be Separated)
6C (More about Dissolving)
National Curriculum Links in KS3
7G (Particle Model of Solids, Liquids and Gases)