A second thought with respect to problem solving came to me after the
previous reply. If you just hit them with more difficult problems, they
will not learn to solve them. You have to hit them with problems that are
at the edge of their zone of proximal development, but not far outside it.
If you make it too difficult they retreat to only memorization. Because
traditional courses do not emphasize using concepts to solve problems, and
do not manage to fix misconceptions, the plug and chug problems were used to
have something the students could do. These work without deep understanding
of the concepts. And they work even when the students do not have good
thinking skills such as proportional reasoning. So getting the students to
understand that the concepts count is absolutely essential. It will not
generally happen if just problems are emphasized.
But the learning cycle approach of exploration first does work with students
who have low level reasoning skills.
Now if you use such problems as evaluations you can certainly make it appear
as if they are learning, but in reality they aren't. Most state testing
relies on a large amount of such evaluations, so it is possible to prep the
students while they still are not learning much.