Question

1. make up your own model that shows conservation of mass:

Explanation:

Conservation of mass means the total mass of reactants equals the total mass of products. First, define the mass of each triangle as $m$, so 4 triangles have a total mass of $4m$, and the square has a mass of $5m$. The total initial mass is the sum of these two. The final box must contain all original components to preserve total mass.

Answer:

In the final empty box, draw the 4 original triangular shapes plus the square with the number 5 inside. The total mass of the left side is $4m + 5m = 9m$, and the right side will also have a total mass of $9m$, demonstrating that mass is conserved (no mass is gained or lost in the process).