# Summary of last weeks work on Variables Predict that there is a relationship between two variables An independent variable is one that is changed or selected.

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Summary of last weeks work on Variables Predict that there is a relationship between two variables An independent variable is one that is changed or selected by you the investigator A dependent variable is measured for each change in your independent variable All other variables become control variables. Type of insulating material affects temperature drop over 10 mins Type of insulating material Drop in temperature over 10mins For a fair test: same volume of water same starting temp of hot water same thickness of material Examples:

Bar charts are for: non continuos variables: categoric, discrete (whole number) quantities. Marks are given for * good use of paper and scale * labelled axes with units * bar lengths correct with labels * bars of constant width YOUR TASK: Plot a bar chart of the following data on the sheet of graph paper provided Your GCSE course work will be given next week. It is important that you know what to do! Temperature Change / 0 C 25 23 30 23 Type of insulation Paper towel Bubble wrap Felt Foil

Bubble wrap 10 20 30 40 50 Temperature change 0 C Type of insulation Paper towel Felt Foil Marks are given for * good use of paper and scale * labelled axes with units * bar lengths correct with labels * bars of constant width Temperature Change / 0 C 25 23 30 23 Type of insulation Paper towel Bubble wrap Felt Foil

Bubble wrap 10 20 30 40 50 Temperature change 0 C Type of insulation Paper towel Felt Foil Marks are given for * good use of paper and scale * labelled axes with units * bar lengths correct with labels * bars of constant width Bar charts are for: non continuos variables: categoric, discrete (whole number) quantities.

Investigative Skills Assignment (ISA) Some background information before we start ISA’s are a new part of your science course. They are designed to take the place of coursework They are worth 25% of your GCSE in science. You get marks for drawing a results table and a graph but most of your marks are scored when you sit a short test and answer questions on the experiment you did. We will tell you what you need to know before the test. If you listen carefully, you will get high marks.

Investigative Skills Assignment (ISA) Are you ready to take notes? Here we go.

Thermal Insulation ISA We are going to investigate how the rate of heat loss from a beaker of hot water, depends upon the type of insulation it has. Thermometer Card lid with hole 200ml of very hot kettle water. CARE! Record the initial temperature of the water and the final temperature after 10 minutes, and then repeat for different types of insulation.

About the experiment In this experiment, which would be the independent variable? (this is the variable that you deliberately change) The type of insulation. How many values should this variable have? (this means how many different types of insulation should we use – give a reason?) Enough so that I could see an effect. This could be 4 types.

About the experiment What is the main measuring instrument in this experiment? Thermometer If we used a digital thermometer that could read to 0.1 ˚C what effect would this have on the precision of our results The results would be more precise. The precision of the results would have increased. What is the precision of a thermometer? – (this is the smallest division on the thermometers scale) 1˚C

About the experiment What are the other variables in this experiment? size of beaker starting temperature of the water the amount of cooling time they get what the beaker is made of the amount of water Why is it important to keep these variables the same throughout the whole experiment? The results would not be valid. If you saw a difference in your results you could not be sure of what was causing the difference

About the experiment How could the reliability of the data (results) be improved? By repeating each experiment several times more, and averaging the results Why would this improve the reliability of the results? This would reduce the effect of random errors like reading the thermometer incorrectly

Insulation Temperature changes after 10 minutes (ºC) 63 Paper towel 4.6 6723 25 Aluminium foil felt Bubble wrap 90 8855 3750 33 88 87 Start ( ºC ) final ( ºC ) Temperature change ( ºC ) Find the anomalous piece of data from this results table. 37 ISA SECTION 2 QUESTIONS

Insulation Temperature changes after 10 minutes (ºC) 63 Paper towel 4.6 6723 25 Aluminium foil felt Bubble wrap 90 8855 5730 33 88 Results chart: 87 Start ( ºC ) final ( ºC ) Temperature change ( ºC )

Insulation Temperature change after 10 minutes (ºC) Paper towel Aluminium foil Felt Bubble wrap Results chart: Start ( ºC ) final ( ºC ) Temperature change ( ºC )

Bubble wrap 10 20 30 40 50 Temperature change 0 C Type of insulation Paper towel Felt Foil Marks are given for * good use of paper and scale * labelled axes with units * bar lengths correct with labels * bars of constant width Bar charts are for: non continuos variables: categoric, discrete (whole number) quantities. Temperature Change / 0 C 25 23 30 23 Type of insulation Paper towel Bubble wrap Felt Foil

Bubble wrap 10 20 30 40 50 Temperature change 0 C Type of insulation Paper towel Felt Foil Marks are given for * good use of paper and scale * labelled axes with units * bar lengths correct with labels * bars of constant width Bar charts are for: non continuos variables: categoric, discrete (whole number) quantities.

Bubble wrap 10 20 30 40 50 Temperature change 0 C Type of insulation Paper towel Felt Foil CONCLUSION: The smallest drop in temperature occurred using ………..……………..….. So ……………………..………….…… is the best insulating material. Bubble wrap Marks are given for * good use of paper and scale * labelled axes with units * bar lengths correct with labels * bars of constant width Bar charts are for: non continuos variables: categoric, discrete (whole number) quantities.

substance Solubility in 10ml of water (g) 20ºC40ºC60ºC salt 4.6 4.14.0 1.41.6 flour coffee sugar3.9 0.30.2 1.81.9 0.4 1.2 Spotting anomalous results 4.6 Try to spot the anomalous piece of data from this results table. Hands up!

substance Solubility in 10ml of water (g) 20ºC40ºC60ºC salt 4.6 4.14.0 1.41.6 flour coffee sugar3.9 0.30.2 1.81.9 0.4 1.2 Using these results, what has more effect on solubility? Is it the temperature or the type of substance? substance salt flour coffee sugar

substance Solubility in 10ml of water (g) 20ºC40ºC60ºC salt 4.6 4.14.0 1.41.6 flour coffee sugar3.9 0.30.2 1.81.9 0.4 1.2 What would be the best way of displaying the results for the 20ºC experiments? a) Bar graphb) Line graph c) Pie chartd) Scatter graph a) Bar graph

substance Solubility in 10ml of water (g) 20ºC40ºC60ºC salt 4.6 4.14.0 1.41.6 flour coffee sugar3.9 0.30.2 1.81.9 0.4 1.2 Why would this be the best way? Plotting data from different substances is not a continuous variable. Different substances are a categoric variable.

Investigative Skills Assignment (ISA) I hope this helps you get high marks! The end!

Bubble wrap 10 20 30 40 50 Temperature change 0 C Type of insulation Paper towel Felt Foil

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