Substitution on the farm.

Mr Johnson

Farm song

http://www.youtube.com/watch?v=w6ySjiDl6-4

Warm Up…

x= 1, y = 2.5, z = 0.5, r = 12 and s = 13.2

You can add, subtract, times and divide.

Write a formula that makes the largest number you can.

Can write a formula that equals or is close to 100?

Level 4 – use symbols to represent unknowns.

You can only use each number once.

Learning Objectives.

Level 4 - use symbols to represent unknowns.

Level 5 – in context use formulae that are expressed in symbols.

Level 7 – generate formulae in context.

Keywords – formula, variable, expression, equation

Ploughing and Sowing.

Farmer Fred wants to plough and sow his field?

How much is it going to cost

him?

So we need to know…• Distance covered by the plough.• Time taken to plough.• Labour cost.• Fuel cost.

4

3

2

1

4

3

2

1

Tractor Price (a) Age (b) kpl (c ) kph with plough (d) kph with seed drill (e)

1 £12,000 15 years 12 8 6

2 £25,000 12 years 9 5 5

3 £100,000 0 years 15 11 5

4 £1,500 19 years 8 8 5

Plough Price (f) Age (g) Width (h) Labour cost (i) = £15 per hour

1 £15,000 0 years 10m

2 £3,000 8 years 5m Size of field ( x by y) = 150m by 350m

3 £2,500 10 years 3m

4 £8,000 5 years 6m Red diesel per litre (j) = £0.85

What have I got to do?

Step 1: Use the formulae to find the cost of ploughing the field.

Step 2: Write in words what these formulae actually mean.

Step 3: Ask for the extension data sheet and use it to find the cost of sowing the field.

Step 4: Write your own formulae for finding the cost of sowing the seed.

EXTENSION.

Is there anything else you could consider in calculating the cost

of ploughing and sowing the field?

Can you make our calculations more accurate?

Plenary.

Come and write a formula that you

made this lesson on the board.

Learning Outcomes.

Level 4 - use symbols to represent unknowns and variables.

Level 5 – in context use formulae that are expressed in symbols.

Level 7 – generate formulae in context.