Eight-year-old Matt is doing well with adding and subtraction. His father asks for suggestions regarding projects that would help increase Matt's understanding of conservation of mass. Of the following projects, which would most help Matt understand conservation of mass?
a) Build a doghouse.
b) Build a sandcastle with a water-filled moat.
c) Stack blocks in a tower.
d) Form vases from blocks of clay.
Answer: Form vases from blocks of clay.