As indifferent as the hand gesture was, the fact that Snape then invited Theo to sit in his office and attempt to work it out meant probably more to Theo than it would have done to any other student.
"Oh... Thank you sir." He almost bit his tongue for the first surprised sound that tripped from his mouth the minute he opened it, but he couldn't help it even though he knew he should know better than to let anything he felt slip, including surprise. Especially surprise.
He stayed where he was in the seat and started studying the box, wanting to take it all into careful and studied consideration before he even started moving parts; it was almost unnatural for a teenage boy to have that much patience, but most teenage boys hadn't been schooled by Theo's father.