It is clearly present in the previous cup. And since students removed 2 drops from that cup and put it in the next cup, the food coloring is therefore present. This question requires a student to infer. Therefore, this may be difficult for some students. Students should infer that some food coloring is present even though they cannot see it because there was some of the food coloring in the drops they transferred from the preceding cups.
Evaporation is the obvious answer, but encourage creativity.
The student worked together and cooperated with their partner throughout the investigation. The student did not cooperate and work well with their partner during the investigation. The student followed the directions throughout the investigation. The student did not follow directions throughout the investigation. Answers were concise and clear, and they showed complete understanding of all processes and procedures.