This NGSS-aligned activity is a student inquiry into the factors that affect seed germination. The activity can be used as an introductory activity for plant studies in biology or as an environmental impact investigation in earth science, environmental science, or agricultural science. Students in pairs or groups must fully design and carry out an investigation that begins with asking a question. They go on to define variables, detail a procedure, collect and analyze data, and share conclusions. After sharing class data, students generate a table of germination factors.
Ensure that students understand and adhere to safe laboratory practices when performing any activity in the classroom or lab. Students should not put their fingers into their mouths during these activities. They should wash and dry their hands after each activity. Demonstrate the protocol for correctly using the instruments and materials necessary to complete the activities, and emphasize the importance of proper usage. Use personal protective equipment, such as safety glasses or goggles, gloves, and aprons when appropriate. Model proper laboratory safety practices for your students and require them to adhere to all laboratory safety rules.
Once investigations are complete, plants can be placed in a resealable bag, frozen, and disposed of in the trash.
Data and Observations
Analysis and Discussion
Check each proposed investigation. Make certain only one factor is being investigated and that variables are defined and can be measured with the equipment available.
Planting depth: If planted too deep, seedlings will not be able to reach the surface and will die. If planted too near the surface, they may dry out and not germinate.
Water: If the soil is too dry, seeds may not be able to absorb enough water to germinate. If the soil is too wet, the seeds may rot.
Temperature: If the soil is too cold, seeds may not germinate.
Weeds: If there are too many weeds, seeds may germinate but the seedlings may be weak.
Fertilizer: If seedlings do not have fertilizer, they may grow poorly. If there is too much fertilizer, the seedlings may be burned.
Light: If there is not enough light, seedlings may grow poorly.
2. Choose a factor from your list and develop a question about seed germination that you can answer through experimentation. The question for investigation is:
Does planting depth affect how well seeds germinate?
3. State a hypothesis for your experiment in this form: “If . . . then . . . because . . .” (If this variable is changed in this way, it will produce this change for this reason.) A hypothesis is not a guess; it is a predicted outcome based on prior knowledge.
If we plant seeds at different depths, the seeds planted deepest may germinate, but the seedlings will not reach the surface. There will be an optimal planting depth.
We will plant radish seeds at different depths and record data on the number of seedlings that emerge above the soil level for each planting depth. Data will be displayed in a data table and as a histogram.
Our research indicates that radish seeds germinate in 2 days under good conditions. On this basis, we plan to allow 10 days from planting to the end of our trial. Since radish is a small seed, we predict that the seeds will germinate best at a shallow planting depth.
Variables that we will control
Variable that we will change
Use point of scissors to make a hole for drainage in the bottoms of four 7-oz cups. Label cups with date planted and planting depth.
Fill cup 1 to a depth of 2 cm with moist potting soil. Scatter 25 radish seeds on the soil surface and fill the cup to a total depth of 8 cm with moist potting soil. Seeds are planted at a depth of 6 cm.
Fill cup 2 to a depth of 4 cm with moist potting soil. Scatter 25 radish seeds on the soil surface and fill the cup to a total depth of 8 cm with moist potting soil. Seeds are planted at a depth of 4 cm.
Fill cup 3 to a depth of 6 cm with moist potting soil. Scatter 25 radish seeds on the soil surface and fill the cup to a total depth of 8 cm with moist potting soil. Seeds are planted at a depth of 2 cm.
Fill cup 4 to a depth of 8 cm with moist potting soil. Scatter 25 radish seeds on the soil surface. Seeds are planted at a depth of 0 cm.
Set completed cups in tray under light bank. Check cups daily and water as needed.
Ten days from planting, count the number of seedlings and record results in the Seedling Data Table. Graph results.
Include a sample data table with variables and units.
Seedling Data Table
How will you analyze the data you collect?
What will be graphed?
Construct sample axes with labels.
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