To know that the distribution of living beings in the garden depends on physical and chemical environment features.

METHOD OBJECTIVES :

 to identify in the garden living and non living components
 to measure with a thermometer, a humidity and light measure device
 to prepare an experiment and interpret the results

MATERIALS :

 a box with three compartments you can light up more or less
 several dozens of fire bugs and woodlouses collected in the garden

PROCEDURES :

Use the worksheet below.

1. Distinguish the living from the non living

During an outing in the garden, observe and list the different elements composing this environment (fauna, flora, rocks, human activity signs…)

Classify the different elements in the table 1

2. Search the different features of the environment

Investigate on the field using the thermometer, the light and humidity measure devices to measure respectively the temperature, the light and the humidity in different areas of the garden. Reporthese measures in the table 2

3. Study the distribution of the living beings according to the environment

The observation of living beings shows they do not seem distributed at random : on a naked stone you never find fern for example but very often lichen.

Photos of lichen on a rock

Prepare an experience showing the habitat preferences of two arthropods : woodlouses and fire bugs.

Put the box (cf. materials) near the light source so as to obtain variable lightings in the three compartments.

Put the fire bugs and the woodlouses in the medium lighted compartment.

After twenty minutes waiting, count the number of woodlouses and fire bugs you find respectively in the three compartments.

From these observations made on the field, what theories can you make about the habitat preference of these arthropods ?

Show the results in a bar chart form and check that the results confirm the theories.

ASSESSMENT :

Capacity for the pupil :

 to identify the garden environment elements
 to conclude that their repartition depends on environment features (humidity, temperature, light and existence or not of a ground corresponding to their preferences.)

Jean-Michel Josse professeur de Sciences de la Vie et de la Terre, Lycée Français Charlemagne de Pointe Noire, Congo Brazzaville