Part one

Observation and Inference: Indoors

Resources:

• Sam & Dave Dig A Hole picture book*

• white board or similar to record ideas

Instructions:

1. Read the book Sam & Dave Dig A Hole. If your library does not have a copy of the book, search for images from the book and use these as a starting point.

2. Discuss the book – what the students saw and what happened during the story. Note: the story is open ended.

3. Discuss observation and its role in science: Science knowledge is based on data derived from direct, or indirect, observations of the natural physical world and often includes measuring something. (TKI Science Online).

4. Discuss inference: An inference is a conclusion you draw from observations – the meaning you make from observations. Understanding the difference is an important step towards being scientifically literate. (TKI Science Online).

5. Read the book again, encouraging students to think like scientists. Ask students to make observations as you read through the story. Record their ideas under the heading I see, reminding students they are limited to what they can see/observe. (Careful observers will notice how the boys and their environment changes as the story progresses.)

6. Ask students to make inferences about the end of the story. Record their ideas under the heading I think. Students must justify their inferences based on their observations.

7. Note if/how student observations changed between the first and second reading.

*Book image is courtesy of: www.macbarnett.com/books/#/sam-dave-dig-a-hole/

Part two

Observation and Inference: Outdoors

Resources:

• spade or soil corer

• sports cone

• groundsheet or sheets of newspaper

• hand lenses

• digital microscope (optional)

• tablets (optional)

Instructions:

1. This activity is best done when the soil is moist. Dry soil is difficult to dig. Muddy soil is messy.

2. Find a suitable place to dig a hole. Avoid high use areas where the soil is likely to be compacted and difficult to dig. Avoid areas where roots my cause difficulties. It also pays to check where services like power or water are placed in the property.

3. Make a PVC soil corer (optional), or use a spade to dig a hole.

4. Dig out a spade width of turf. Place the turf on the groundsheet or newsprint.

5. Continue to dig down, empty the spade or corer to make a soil profile. A profile shows what the soil looks like from the surface downward.

6. Notice if the soil changes as you dig down. Use your eyes and your hands to observe. Does it have the same colour? Does it feel the same if you rub it between your fingers?

7. Continue to dig until it gets too difficult.

8. Mark the site with a sports cone to alert others to the hole.

9. Carefully carry the soil inside. If the profile is too heavy, remove handfuls of soil and make a similar profile.

10. Use hand lenses or digital microscopes to examine the soil. Look through the turf and roots for soil animals (earthworms or insects). Break apart clods of soil to examine what is inside or to see if the soil colours change. Measure the length/depth of plant roots.

11. Are there any inferences that students can make based on their observations? (Large clods or lack of earthworms may mean soil is poor quality. Mottled colour may mean the soil is poorly drained.)

12. Use the digital tablets to record student observations and inferences as they discuss/handle the soil.

13. Return the soil and turf to the hole.

14. Choose another part of the school ground to sample. For example, an area at the top or bottom of a slope, next to a fence line or in an out of bounds area. Compare the soil. Dig deeper.

Find the instructions for the home-made soil corer at: sciencelearn.org.nz/resources/675-making-a-core-sample.

The soil corer image is courtesy of the Science Learning Hub.

S-map Online is a digital soil map of New Zealand. Use it to learn more about the soil in your area.

Check out the Science Learning Hug student activity: Visual Soil Assessment. The activity involves digging up a 20cm cube of soil to examine the soil structure and porosity and look for earthworms.

Older students or landowners can perform the more extensive Visual Soil Assessment that famers and other professionals use.