A student has two objects. Object 1 has a mass of 10 g and a volume of 5 cubic centimeters. Object 2 has a mass of 10 g and a volume of 20 cubic centimeters. If both objects are placed in water, which will float and why?

Object one will float because the mass and volume are lighter than object two. Object one also has a smaller surface area.

(+)(+)=+++.
(
a
+
b
)
(
c
+
d
)
=
a
c
+
a
d
+
b
c
+
b
d
.

It’s counterproductive because it only applies to products of binomials. It doesn’t help for expanding (++)(+)
(
a
+
b
+
c
)
(
d
+
e
)
or even (+).
a
(
b
+
d
)
.
It would be better if students learned the general distributivity law: to expand the product of two sums of any number of terms, take all the products of terms in the first times terms in the second and sum them together. For example,

(++)(+)=+++++.
(
a
+
b
+
c
)
(
d
+
e
)
=
a
d
+
a
e
+
b
d
+
b
e
+
c
d
+
c
e
.

It includes the product of two binomials as a special case.