Answer:
Projects/encourages
Step-by-step explanation:
Innovative use of computers in the classroom allows students to undertake projects that encourages them to be both analytical and intellectually adventurous.
The error in this sentence is the use of "encourages," where there is a subject-verb disagreement. The subject "projects" is plural, but the verb "encourages" is singular. The sentence should be:
Innovative use of computers in the classroom allows students to undertake projects that encourage them to be both analytical and intellectually adventurous.