1. Substitution on the farm. Mr Johnson

2. Farm song http://www.youtube.com/watch?v=fJyfh-9b8ZA http://www.youtube.com/watch?v=w6ySjiDl6-4

3. CODEWORDS. If this is the code… What does this say? A=1, B=2, C=3, etc. 9 12,15,22,5 8,1,19,8,18 Can you make up your own code and write a sentence for person next to you to solve?

4. Ploughing and Sowing. Farmer Fred wants to plough his field? How much is it going to cost him? What do we need to consider?

23. So what information do we need?

24. So we need to know… The size of the field. The size of the plough. The speed of the tractor with the plough. Labour cost. Fuel cost.

25. 4 3 2 1

26. 4 3 2 1

27. TractorPrice (a)kpl (c ) kph with plough (d)kph with seed drill (e) 1£12,0001286 2£25,000955 3£100,00015115 4£1,500885 Plough Price (f)Width (h) Labour cost (i) = £15 per hour 1£15,00010m 2£3,0005mSize of field ( x by y) = 150m by 300m 3£2,5003m 4£8,0006mRed diesel per litre (j) = £0.85

29. What now? Choose a tractor and plough. Calculate the cost of ploughing the field using your chosen tractor. Present your findings clearly of the A3 sheet. Prepare a presentation so that you can share you results with the class. Extension. Can you find the best combination of tractor and plough?

30. So what have we learnt? Letters can be used to represent variables.

31. On your Mini Whiteboards… 1.If x = 2 what is x + 2? 2.If y = 3 what is y – 2? 3.If p = 38 and q = 17 what is p + q? 4.If r = 12 and z = 27 what is r – z? 5.If s = 15, t = 2 and x = 5 what is s + t – x ? NC level 5A

32. On your Mini Whiteboards… X=1, Y=2, Z=7, R=12, S=25 1. 2X = 2. 3R = 3. 2R + 5Z = 4. 3Z + 2Y – 2X = IF

33. On you Mini Whiteboards… If X=3, Y=6, Z=12, R=25, S=5 solve these...

34. Now try these in your books…