U1C1A4

Evaluating Experimental Design

Exp 1: Heating Earth Materials

• 1Q: If the type of Earth’s material is changed, what happens to the temperature of the material as it is heated by sunlight?

• 2. MV: type of Earth materials

• RV: temperature of Earth materials as heated by sunlight

3. MV values: twp types of Earth materials - dirt and water

• 4. RV is measured in temperature, Degrees C, with a thermometer

• 5. Same: buckets, amount of sunlight, thermometers and their placement, time in the sun

• 6. Differences other than MV and RV:

• Yes, the amount of Earth material

• Full bucket soil, 1/2 bucket water

• 7. No, this is not a fair test - more than one variable - see answer to #6.

• (amount of Earth material varies)

Exp 2: Freezing Water

• 1Q: If hot and cold water are placed in a freezer, which freezes more quickly?

• 2. MV: water temperature

• RV: time it takes for water to freeze

• 3. MV values: tray of hot water, tray of cold water

• 4. RV measured by time intervals, and observing if water frozen

• 5. Same/control:

• tray size

• amount of water added in each tray

• liquid used is water

• 15 minute interval checks

• both put in the same freezer

• 6. Different other than MV and RV: Yes.

• The trays are made out of different material (metal, plastic), and they are place on different shelves in the freezer

• (top, bottom)

• 7. This experiment is NOT a fair test because of #6, more than one variable (tray material and location).

Exp 3: Corn

• 1Q: If the type of corn seed is changed, what happens to its growth rate and health in crowded conditions?

• 2. MV: type of corn seed

• RV: growth rate and health

• 3. MV value: seed types 1,2,3,4

• 4. RV measured by observation of the plant health, and measurement/count of growth

• 5. Same/control:

• same number of seeds in each pot, same pot sizes

• same depth planted

• same amount of water

• all checked at same time (3 weeks)

• 6. Different other than MV and RV: Yes, the type of soil in each pot is different

• 7. No this is not a fair experiment, because there is more than 1 variable (soil type)

• Conclusion: You should be able to answer/identify the 7 criteria used in this activity to determine if an experiment is designed fairly:

• 1Q• 2: MV, RV• 3: values MV• 4. RV measurement• 5. Same controls• 6. Different variables• 7. Answer (Fair, yes or no)

• Share/Communicate:

• See the “How to Analyze an Experimental Design and determine if the Experiment is a Fair test”