A description and reflection of a math lesson I taught in a 4th grade classroom

2. The Task
A rope ladder with 8 rungs that are 9 inches
apart is hanging over the side of a pool. The first
rung is 9 inches from the bottom of the empty
pool. If we fill the pool at a rate of 1 foot per
hour, how long will it take to reach the top rung
of the ladder?

3. Mathematical Thinking
Actual-sized ladder
Used problem solving strategies
Breaking it down in steps
I asked:
“What did you do first?”
“What do you need to do next?”
“Why did you choose to solve it this way?”

4. Mathematical Thinking
Allowed students to choose own partners..
Had 3 partner groups share their work and how
they solved the problem (each had a different
strategy)
Strategies were: act it out, draw a picture, write an
equation, make a chart
Was surprised by the work that the partner groups
produced (Andrew and David)

5. Problem Solving Strategies

6. Nang’s WorkTAG

8. Pedagogical Knowledge
Effective moves:
Preparing steps to break down the task, but not
showing the students until about half the class was
ready to move on to that step/ needed it
Encouraged students to make T-charts to organize
info (CT gave the idea)
Life-sized ladder made visualizing the problem
easier/ could act it out

9. Pedagogical Knowledge

10. Professional Growth
How I would change the lesson:
Have more closure
Bring it back to the question to make the context
more real:
Will the pool be filled up in time for the pool party?
Instead of just: “It will take 6 hours”
Allow students to make life-sized ladders on butcher
paper

11. Professional Growth
Ask more questions to students when they
shared their work
Introduce the task in a different way in order to
intimidate the students less

12. Questions?
How else could I introduce this task? The students
had no idea what to do when they first read it.
How would I make this task more “real” to the
students?
I thought about extending the lesson using a “not so
nice” number for inches, such as it would take 1 hour
to fill 14 inches, instead of 1 foot… but what other
way could I extend this lesson to make it more
difficult now that the concept is grasped?