Primary School Agriculture: Volume I: Pedagogy (GTZ, 1985, 144 p.) 
Part III: Examples for practical use 
2. Lesson notes 

(some more examples)
Another problem is taken from the observation of planting distances on a maize plot at a school farm. Two rows planted by different pupils according to the same standard planting distance  25 cm  have been measured after germination. The results are as given in the next table.
Row A 
Row B 
27 
24 
27 
26 
28 
23 
35 
27 
29. 
25 
22 
25 
33 
26 
32 
26 
29 
25 
31 
26 
38 
32 
30 
22 
32 
25 
29 
27 
30 
25 
28 
23 
34 
24 
33 
25 
35 
22 
24 
27 
27 
25.5 
33 
30 

24.5 

25 

26.5 

25 

25.5 

26 

24 

29 
Average: 30.27 cm 
Average: 25.5 cm 
Range: 3822=16cm 
Range: 3222 = 10cm 
22 
1 
24 
1 
27 
3 
28 
2 
29 
3 
30 
2 
31 
1 
32 
2 
33 
3 
34 
1 
35 
2 
38 
1 
Total 
22 
If a measuring rod marked with centimeters is available measuring is quite fast. It shows how despite a standard planting distance (25 cm) obtained by using a stick cut to size, the actual distance can be consistently greater or smaller  ask for the reasons (fatigue, wish to get the work done quickly, planter being rushed, wrongly cut stick, insufficient routine), and that even where on average the standard distance is well approximated, there are variations due to some or all of the factors outlined above.
Problems:
1. Which planting distances occur several times? How often do they occur?
Group identical measurements and order them according to size. The second table shows how this would be done for row A.
Make a bar chart. You might group the measurements still
further, e.g.
2224 cm
2527 cm
2830 cm in order to have fewer bars in
your chart and larger numbers for each bar.
2. Calculate the average planting distance in each row.
3. Using the range (highest planting distance  lowest planting distance in each row) determine which pupil has been the more accurate in his planting.
The third problem was formulated after a class had measured a farm plot that had just been tilled. Twelve ridges were ready for planting. On p. 136 is the table of measurements.
Problems:
1. Calculate
 the average length of the ridges,
 the average width of
the ridges,
 the average height of the ridges,
 the average width of
the furrows.
2. Make a scale drawing showing each ridge.
3. What is the length and the width of the total plot?
4. What is the average area per ridge? (average length x number of ridges)
5. What is the net planting area of the plot? (average area x number of ridges)
Ridge No. 
Length 
Width 
Height 
Furrow  

m 
cm 
m 
cm 
m 
cm 
m 
cm 
1 
5 
56  
90    
65 
2 
5 
30  
90  
21  
65 
3 
5 
60  
74  
35  
61 
4 
4 
60  
65  
20  
40 
5 
5 
56  
90  
12  
65 
6 
5 
30  
90  
21  
65 
7 
4 
60  
90  
23  
64 
8 
5 
35  
85  
30  
60 
9 
4 
34  
80  
20  
65 
10 
4 
60 
1 
17  
21  
65 
11 
4 
34  
80  
20  
64 
12 
3 
 
1 
  
21  
65 