Astronaut in space

The scientific method

The essence of all good science lies in a process called "the scientific method." The scientific method uses objective experimentation to predict, verify, or refute, an assertion made by a theory. Based on the results of the experiment(s), the theory is modified. The processes involved with prediction, observation, verification (or refuting) are repeated, continually testing and modifying the theory until the theory fits all possible experimental observations. Then the theory is considered a scientific law.

The scientific method

Transparency master

The diagram above shows a simplified flow chart of the scientific method. One can "enter" the flow chart at any point in the cycle. Generally however, one starts with a theory, a prediction, or an observation.

The Tomatosphere project

The Tomatosphere Project is a scientific investigation in which the germination properties of seeds are examined. Based on the outcome of this investigation conclusions will be drawn which will facilitate the planning of long term missions on the International Space Station, to the Moon and eventually, to the planet Mars.


Seeds are exceptionally resistant to damage from environmental extremes.

We know from experience that plant seeds are hardy and resist damage from a wide range of environmental conditions on Earth, including heat, cold, and drought, but how will they react to having spent 22 months in space on the ISS and travelled over 450 million kilometres?

Each class receives two packages with a total of 60 seeds - 30 of each of the two types - the control group (with no treatment) and the group that came back with Commander Chris Hadfield in May, 2013, following 22 months on the ISS. For details on the simulation, see Seed Treatment for 2013.  Note that the seeds are packed by WEIGHT and that consequently, there can be a +/-5 variance in the number of seeds you receive. When you received your seeds, the accompanying note suggested strongly that you check the number of seeds in each package.

Because the first tomato seeds will normally germinate in 5-7 days, it is recommended that the seeds be planted later in the week, and NOT before a holiday Monday. This will allow the students the best opportunity to see the germination process taking place the following week.

Scientific method theory


Based on what we know about seeds what do we think will happen when they are exposed to the seeds exposed to these conditions?

No effect? Disastrous effect? Something in between these two extremes?

We cannot be certain that our prediction is valid. We must test our prediction.

Scientific method theory


Seeds exposed to each of the two conditions are provided.

The planting of the seed treatments will be measured and compared.

The attempted germination of all seeds should be undertaken simultaneously and under identical conditions in order to control as many variables as possible.

Plant the two types of seeds provided. Plant AT LEAST 20 of each type. You may plant all the seeds if you wish.

Record the number of seeds planted for your submission of results.

Scientific method theory


The number of seeds which germinate in each group will be recorded.

Observations should be taken daily and recorded accurately. Anecdotal information that might prove to be useful later when the analysis of the data takes place should be noted (e.g. accidents, changes in room temperature over weekends).

Scientific method theory

Assuring objectivity

The two sets are labeled "T" and "V". The origin of the seeds will be revealed following the completion of the experiment and your submission of the results (click here to submit your results online). There is a one-page overview of this component of the process called "Recording and reporting your results". Click here to access the data collection form.

This is called a "blind study"; it is designed to eliminate unintentional bias in the experimental process.

Biased observations

Sometimes our expectations determine the outcome of an experiment, such as experimenting with the taste of new foods. Presented with a big, fat, roasted grub (considered a fine delicacy in some societies), we generally expect that it will taste awful... and if we conjure up enough bravery to try it, it usually does taste awful upon taking the first bite, even though it may taste exactly like peanuts or cashews... our expectations influence or even prejudice our observations.

Similarly, in a scientific investigation, it is possible to influence our observations by unconsciously tampering with the experimental controls or biasing our observations. For example, moving a specific group of tomato seeds to a warmer location after the experiment has begun because we expect or hope that this specific group of seeds will germinate better is a case of tampering with the experimental controls.

If we record a dead, partially germinated, seed as "unsuccessfully germinated" in one group while recording such a seed in a similar state as having been "successfully germinated" in a different group (because we were fairly certain the second group should be more successful); this would be an example of inaccurate or biased reporting.

Biased observations are usually made unconsciously by the observer and are rarely deliberate attempts to misrepresent the data.

For this reason, blind studies are used for many scientific studies, including the Tomatosphere project. As a result, teachers (and students) will not know the sources of the two groups of seeds until the experiment is complete and the results submitted.