Primary School Agriculture: Volume I: Pedagogy (GTZ, 1985, 144 p.) 
Part III: Examples for practical use 
1. Teaching subunits 
This subunit gives the details of how to evaluate an experiment. It does so sticking very closely to one example. But the general procedure is the same for all experiments.
The example is drawn from Mudeka Government School. Under the guidance of IPARBuea, the school grew a large number of pineapples on an area of 60 m x 56 m = 3 360 m². Two different planting methods were used. On part of the farm, pineapples are 1.8 m apart from each other in each direction. This is called single row planting. On another part of the farm, pineapples are planted in double rows, staggered, the distance of the plants in each of the double rows is 60 cm, the two rows forming one double row are 60 cm apart, and the centre line of one double row is 2.4 m apart from the centre of the next one. This is called double row planting.
The Problem
Which of the planting methods is superior, and
should therefore be recommended to farmers? How can this question be answered?
One important yardstick certainly is the yield, to be got following either method. Two questions might be asked in this respect:
 Which planting method produces higher yields per area?
 Which planting method produces a higher return over costs (i.e. the money initially spent to plant the crop)?The problem is made difficult by the fact that pineapples are a perennial crop. Unlike coffee or cocoa, the time between planting and first harvest, and between first harvest and the first ratoon crop can vary a lot so that there is no clearcut, short, welldetermined peak harvesting time. The procedure proposed provides an assessment of the harvest at the time of measurement and an estimate of future harvests It is best done towards the end of the first heavy harvest. The answer to our problem will be provided by two comparisons:
 yield per standard area: No. of fruits harvested per square meter under single row planting and under double row planting;
 return over costs: Value of fruits harvested at time of measurement compared with cost of planting material for single row planting and for double row planting.
Planting Methods Used in the Experiment
1. Objectives Concerning Farm Work
none
2. Objectives in Agriculture
 Pupils know the advantages and disadvantages of different planting distances.
 Pupils know that in the case of single cropping, planting distances can be smaller and plant populations higher than in the case of multiple cropping.
 Pupils know the practical use of the concept of plant population per hectare.
 Pupils know simple indicators or measures of profitability.
3. Skill Development
a) Study Skills
 Pupils are able to find out the results of a simple
experiment.
 Pupils are able to count relatively large numbers of objects
exactly.
 Pupils are able to make simple estimates
 e.g. forecasting
next year's crop, forecasting price movements for a given crop.
b) Social Skills
 Pupils are able to work in teams of two to three children during outdoor and classroom activities.
A. Introductory Lesson
Objectives
 Pupils know the purpose of the teaching
unit.
 Pupils are able to recall the main facts of the experiment.

Pupils are able to recall the main facts about the pineapple plant and pineapple
farming.
 Pupils have a record sheet ready.
 Pupils are grouped in
teams.
Lesson
(the day before the observation or immediately
preceding the observations on the farm)
 Revise the reasons for setting the pineapple experiment.
 Explain the problem of the subunit: how can we get an answer to our question from the experiment?
 Discuss the comparison in terms of yield per hectare.
 Discuss ways to assess the yield of a pineapple farm considering the fact that fruits do not get ready for harvesting at the same time.
 Propose a record sheet and let pupils copy it into their exercise books.
 Group the pupils in teams of two or three children.
Record Sheet     
Row 
(1) 
(2) 
(3) 
(4) 
No. 
Total No. of Plants 
Plants Harvested 
No. of Plants with Unripe Fruits 
No. of Plants without any Fruits 
B. Practical Work
Objectives
 Knowing the number of plants harvested, bearing
fruit, and remaining without fruits;
 pupils are able to count correctly and
to record their findings correctly using the record sheet proposed in the
preceding lesson.
Outdoor Activity
The teams got to their assigned rows and
start counting. One team member counts, the other one enters the information in
the record sheet. Team members take turns. Each team counts at least one row
which has already been counted by another team. This will help crosschecking
and gives an idea of the incidence of error.
When all the rows have been counted, the teacher checks a few rows himself.
C. Followup Lessons
1. Assembling the Observations
Objectives
 Pupils and teacher have the complete picture of
all observations row by row.
 Pupils and teacher have an idea of the errors
made during counting.
 Pupils know the total number of pineapples harvested
and the number of fruits to be expected during the season.
 The observations
are assembled in a way which permits further analysis in class.
Lesson
(immediately after the outdoor activity)
The teacher draws the observation sheet on the blackboard. The teams read out their observations starting with row 1 and going up to the last row. For each row there are at least two readings. Major differences between them give rise to a recheck on the farm. Differences of 1 or 3 plants are minor differences. Discuss possible reasons for these errors.
Teams are asked to copy the complete table of observations. The following sums are given to the teams for work:
a) For each row, add columns 2, 3, and 4. The total must agree
with the entry in column 1.
b) For each of the two blocks (single row
planting and double row planting), add
 the total number of plants (column 1),
 the number of
plants harvested (column 2),
 the number of plants with unripe fruits
(column 3),
 the number of plants without any fruits (column 4).
Data Collected by Pupils and Assembled in a Table Ready for Evaluation
Single Row Planting  

(1) 
(2) 
(3) 
(4) 
Row No. 
No. of Plants 
No of Plants Harvested 
No. of Plants with Unripe Fruits 
No. of Plants without any Fruits 
1 
35 
7 
2 
26 
2 
32 
7 
9 
16 
3 
35 
9 
3 
23 
4 
37 
10 
1 
26 
5 
32 
13 
2 
17 
6 
25 
6 
1 
18 
7 
50 
6 
1 
43 
8 
23 
3 
1 
19 
9 
37 
10 
1 
26 
10 
12 
6 
 
6 
12 
11 
5 
 
6 
13 
13 
5 
1 
7 
14 
24 
9 
1 
14 
15 
12 
4 
2 
6 
16 
11 
3 
 
8 
17 
12 
1 
 
11 
18 
26 
5 
1 
20 
19 
12 
3 
 
9 
20 
22 
3 
2 
17 
21 
33 
7 
2 
24 
22 
19 
3 
1 
15 
23 
30 
5 
 
25 
24 
20 
3 
2 
15 
Total 
585 
148 
34 
403 
Double Row Planting  
25 
102 
34 
13 
55 
26 
95 
15 
3 
77 
27 
100 
25 
3 
72 
28 
106 
34 
3 
69 
29 
79 
14 
5 
60 
30 
86 
24 
2 
60 
31 
84 
25 
1 
58 
32 
95 
27 
8 
60 
33 
94 
30 
4 
60 
34 
42 
6 
6 
30 
35 
42 
19 
1 
22 
36 
42 
13 
4 
25 
37 
38 
11 
 
27 
38 
44 
14 
 
30 
39 
34 
10 
5 
19 
40 
43 
12 
13 
18 
41 
42 
14 
2 
26 
Total 
1168 
327 
77 
768 
Grand Total 
1753 
475 
107 
1171 
2. The Yield in Single Row Planting
Objectives
 Pupils know the yield of the single row block in
terms of fruits per hectare.
 Pupils know how to calculate this yield using
the information available.
Lesson
 Get the following data for the single row block:
the total number of plants (from the table of
observation),
the planting distance (from the farm records or from
measurements to be done by a few pupils).
 Calculate the area occupied by each plant. It is the planting distance squared: 1.8 m x 1.8 m = 3.24 m².
 Calculate the total area of the single row block (in m² ): total number of plants x area per plant; 585 x 3.24 m² = 1895.40 m².
Note: If the area for the two blocks has been carefully measured at planting, this information can be taken directly from the records.
 Get the total number of pineapples harvested on the single row block from the table of observations.
 Calculate the number of pineapples per hectare: (total number of pineapples harvested x 10 000): total area of single row block; (148 x 10000): 1895.40 m² = 781.
3. The Yield in Double Row Planting
Objectives
 Pupils know the yield of the double row block in
terms of fruits per hectare.
 Pupils know how to calculate this yield.

Pupils know how to calculate the area per plant in double row planting.
Lesson
 Pupils are asked to calculate the yield per hectare
in double row planting using the same procedure as in the preceding lesson. They
will need some help in calculating the area of the double row block if this area
has not been recorded in the farm records. The planting distance in double row
planting is as follows: between the double rows, the distance from the centre of
one double row to the next is 2.4 m. Each plant can use half that distance, 1.2
m. Along the rows, the distance is 60 cm. Each plant therefore occupies an area
of 1.2 m x 0.6 m = 0.72 m² (see the illustration p. 111 for an example).
 Let the teamswork through the problem after they know the area per plant and repeat the calculations for the whole class.
Total area of the double row block = number of plants x area of double row block/ plant; 1168 x 0.72 m² = 840.96 m².
Yield per hectare = (327 x 10000 m²): 840.96 m² = 3 888.
4. Comparison Between Single and Double Row Planting
Objectives
 Pupils are able to draw conclusions from
comparisons.
 Pupils are able to put conclusions in writing.
Lesson
 The teacher asks the class to compare the yields from the two blocks. He/she draws a simple table on the blackboard (see below) and asks what information should be used for comparison.
 Ask teams to make sentences about the differences observed.
 Let the teams read out their observations and remarks and arrive at a common text.
 Ask teams to think about reasons why the double row block, where pineapples are "choked up", does not have the same or a lower yield than the single row block where pineapples have much more space.
 Ask for reasons why the yield per area in double row planting is even higher than in single row planting.
 Discuss the reasons advanced by the teams and arrive at a common summary.
Method of Planting 
Single Row 
Double Row 
Fruits Harvested on each Block 
148 
327 
Fruits per Hectare 
781 
3888 
Planting Distance 
1.8 m x 1.8 m 
1.2 m x 0.6 m 
Area per Plant 
3.24 m² 
0.72 m² 
Plant Population per Hectare 
3086 
13888 
5. Expected Yields at the End of the Season
Objectives
 Pupils know how to make short term forecasts and
to justify them.
Lesson
 The teacher puts the following problem to the
pupils: "So far, only the pineapples harvested have been counted in the yield.
Is this reasonable? How can we take the unripe fruits into account?"  We do not
know when the unripe fruits will get ripe.
Can we make an assumption? Assume that all fruits will get ready by the end of the current pineapple season. We can now estimate the total yield of the first season:
single row planting:  
harvested 
148 
unripe 
34 
total 
182 
double row planting:  
harvested 
327 
unripe 
73 
total 
400 
 Ask the class to do the calculations on yield with the total number of fruits instead of the number of fruits harvested. All other figures remain the same. The results should be: single row planting: 960 fruits per hectare; double row planting 4 756 fruits per hectare.
 Ask the pupils whether the result of the preceding lesson concerning the difference between the planting methods is confirmed, whether the difference has narrowed down or grown bigger. This can be seen by asking how much bigger the double row harvest is than the single row harvest The way to do it is by a division:
double row yield/single row yield = 3888/781 = 4.97(harvested fruits) and 4756/960 = 4.95
There is a very slight difference only which can be neglected. For both yield estimates the yield in double row planting is nearly five times bigger than the yield in single row planting.
6. The Profitability of the two Planting Methods
Objectives
 Pupils know how to do a simple calculation of
profit.
 Pupils can draw conclusions from two different ways of evaluating
the experiment: yield in terms of fruit, and cash income.
Lesson
 Confront pupils with the question whether the class has made
any profit on pineapple farming.
 Discuss the notion of profit: income 
costs = profit or loss.
 From the sales records tell the class the total
income from the pineapples. If a large number of fruits have been given out
free, calculate their cash value. In order to do this, work out the average
price per fruit sold and multiply the total number of fruits harvested by the
average price.
Up to the date of evaluating the experiment, 259 pineapples had been sold, yielding an income of 14340 frs CFA. The average price per pineapple therefore was 14340 frs: 259 = 55.37 frs CFA.The cash value of the harvest in the two blocks is:
single row planting  
harvested fruits 
148 
cash value 
8195 
double row planting  
harvested fruits 
327 
cash value 
18106 
 Ask the class what counts as cost. Argue that only suckers should be counted since the farm land and teacher's and pupils' labour were actually free.
 Calculate the average cost of the suckers. Consider that 1 800 suckers were bought at 11 500 frs CFA, but that only 1 753 of them survived. Since only the surviving plants produce a fruit, they alone can be charged with the total cost of the farm. The average cost per sucker therefore is 11 500 frs CFA: 1 753 plants = 6.56 frs CFA/plant
 Ask teams to calculate the cost of the two blocks separately. This is done by multiplying the number of plants in each of them by the average cost per plant:
single row planting  
total number of plants 
585 
cost 
3838 frs CFA 
double row planting  
total number of plants 
1168 
cost 
7662 frs CFA 
Let the class calculate the profit of the two blocks:
single row planting  
cash value 
8195 frs CFA 
cost 
3838 frs CFA 
profit 
4357 frs CFA 
double row planting  
cash value 
18106 frs CFA 
cost 
7662 frs CFA 
profit 
10444 frs CFA 
The profit from double row planting is much higher than that from single row planting.
 Ask the class to divide the income by the costs. What does the result mean? It says by how much the income has multiplied, the costs, i.e. the money invested. The results should be: single row planting: 2.14; double row planting: 2.36.
Costs for planting material have been recovered with the two planting methods. But in single planting, the yield valued in monetary terms is about 2.1 times the cost, whereas in double row planting, it is about 2.3 times the cost. Therefore, double planting is advantageous.
7. Drawing Conclusions from the Experiment
Objectives
 Pupils draw conclusions from the experiment.
Lesson
 Ask pupils what they would recommend a farmer to do
if he or she planned to farm pineapples.
 Let them repeat all the
results:
 Double row planting uses the soil more efficiently.
Double row planting produces yields per hectare which are five times higher than in single row planting.
Double row planting means higher cost per hectare.
Double row planting means much higher income per hectare.
Farmers should always do double row planting and use the remaining land for other crops.