The printed record of the session will provide a workflow for the teacher of the pupil's path through the module and give insight to their engagement with the content.
Formal assessment could be to assign the pupils follow-up research into one of the topics of most interest to them e.g. submarines, ice-bergs, estuaries etc. The research could be presented as a report, project, poster or oral presentation and could be a team or individual effort.
Debriefing: Children can be asked to explain what they have found out from the activities which they engaged with on-line or from the actual floating and sinking investigations which they have undertaken. For example, they might be asked -In what ways were the objects that floated alike? In what ways were the liquids alike? Different?
Ask the children to explain by asking open-questions Can you tell me about what you noticed about objects which floated? Sank?
Ask children to design something and to explain their design rationale using diagrams Design something that will keep an elephant afloat in a large lake.
Children can engage in working out an answer to the questions posed below individually, in pairs or in small groups. Children should be encouraged to record their observations using text and diagrams.
Q 1. 'You have been given a ball of mala that sinks. Describe 3 changes you could make so that it floats.' Children should be encouraged to explore this by trying things out for themselves e.g.
- Make it into a boat-shape;
- Attach something like a balloon or a table-tennis ball to the mala ball;
- Wrap the mala around a ping-pong ball
This will help with the concept of average density - adding objects with air to the mala, or changing the shape of the mala so there is some air trapped, all change the average density and allow the mala to float. Add cent coins to each 'boat' to see how many the boat can hold before it sinks.
Explain the difference between salt water and fresh water e.g. A volume of salt water weighs more than an equal volume of freshwater; the salt water is more dense than the fresh water. Children could explore this in class by adding salt to water and weighing it.
Q2: Do you think it matters how hot the water is when you add in the salt? Tricky - perhaps again the children could explore it in class. They may have everyday experience from stirring sugar in tea. The physics answer is that the hotter the liquid, the more 'space' there is between the water molecules (it is slowly turning into steam), so the more 'room' there is for salt to dissolve. It means that you can dissolve more salt into water when it is hot than when it is cold.
Q3: Do you think raisins would float in water? Probably not. What would happen if you used a fizzy drink instead of water? Fizzy drink is denser than water because it is a solution of sugar in water. So, the raisins might float in the fizzy drink, but not in the water. Can you test your prediction? Of course - do the experiment!
Q4: Are all fizzy drinks the same? Take a can of a soft drink and its diet counterpart and put them into a tank of water. One will float and one will sink - but which one? Ask the children to make predictions and do the experiment. The regular drink will sink because it contains sugar which increases its average density, making it sink. The sweetener used in diet drinks is less dense than sugar and also is used in smaller quantities than sugar, so it can float. In addition, the fizz in the drink is caused by bubbles of gas, which is less dense than water, so the overall density is less than the density of water and the can floats.
Q5: What is the difference between a prediction and a guess?
Q6: Does how deep the water is affect the way an object floats?
Use bowls of water and/or tanks of water with different depths of water-deep, not deep, very deep etc.
Make a simple boat(s) from aluminium foil. Observe what happens when the boat is placed in water that is deep and water that is not so deep. Does the depth of the water make any difference to how well the boat floats? What other things might affect the way the boat floats?