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 only use each number once.
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.
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?
So we need to know…
• Distance covered by the plough.
• Time taken to plough.
• Labour cost.
• Fuel cost.
2
4
3
1
2
4
1
3
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)
1
£15,000 0 years
10m
2
£3,000
8 years
5m
3
£2,500 10 years
3m
4
£8,000
6m
5 years
Labour cost (i) = £15 per hour
Size of field ( x by y) = 150m by 350m
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.