# CrowBot: An Educational Robotic System for Growing Food
## 7 Experiments and Results
During the experiment, the sensor data from all nine GrowBots could be monitored in real-time on the web-interface of the server, and further, the data was stored on the server for analysis of the full dataset. Figure 10 shows the web-interface visualization of the sensor data for one of the GrowBots. Here it can be observed how the temperature, humidity and CO\({}_{2}\) level are dependent variables, and how they consistently changed based on the control of the light color and level. As can be seen with the example in Figure 15, as a result of the experiment, it was found that clear visible growth of the plants only happens after a few weeks of growing of the seeds. This informed the educational material to include a recommendation for the teacher (and pupils) to perform germination and seed growing in cups for 2-3 weeks prior to initiating the growth in the GrowBot. In this way, the teacher and pupils can select the cups with successful seed growth to be put into the GrowBot to ensure an interesting growth development and comparison between programs to be performed by the pupils. Figure 14: Seven of the nine GrowBots used in the lab for the experiment. At the end of the experiment after 43 days, all plants were harvested, including careful separation of the roots from the rockwood (see Figure 16 for examples). Afterwards, the roots were carefully dissected from the plant, and the rest of the plant was used for  
Figure 15: Photos from the camera mounted inside one of the GrowBots showing the growth of a basil plant in a GrowBot during 43 days (images from the last 35 days). further measurement of height, weight, and leaf width. The results of the experiment are summarized in Table 4. All the plants grown in the GrowBots with blue light had a mean height of 4.3 cm at the time of harvest at the end of the experiment, while the plants in the GrowBots with the red light had a mean height of 1.0 cm. The mean weight of the plants without roots from GrowBots with blue light was 1.31 g, and from GrowBots with red light the mean weight was 0.05 g. The mean width of the three largest leaves from the GrowBots with blue light was 1.13 cm, whereas it was 0.19 cm for the leaves from the GrowBots with red light. The statistical analysis with the unpaired t-test showed that the difference in plant height and leaf width between the blue light and red light conditions is statistically significant at \(p<0.01\) (see Table 4). Figure 16: **(Top)**: The ray with growth of green lettuce, red lettuce, basil, and parsley after 43 days in a GrowBot. Bottom: Harvest of one row of plants grown in two different GrowBots with each program during the 43 day experiments, including their roots (**left**): basil (from the 2 nd row of a GrowBot named [PERSON]), (**right**): parsley (from the 1 st row of a GrowBot named [PERSON]). Even if there was no germination and seed growing in cups for 2-3 weeks prior to initiating the growth in the GrowBots, it is possible to observe the difference between growth of food plants in blue and red light conditions. Hence, the experiment would confirm the hypothesis for the teacher and pupils that initial growth under blue light would produce stronger and higher food plants than under red light conditions. A number of seeds did not germinate, as can be seen on Figure 15, and this may have influenced the results of the experiments, so a germination process may be advisable for the pupils before starting the growth experiments, in order to have a clear basis for comparison and testing their hypotheses. The results verified that the GrowBot technology can work as a controllable environment for some food plant growth, which was the main aim as the foundation for a novel educational robotic system. To verify the suitability and robustness of the GrowBots in school use, we performed a pilot test with 6 GrowBots in the school Tinderhej Skole, in Denmark.