U2 Day 13-14: PD Discussion Topic

Exploring Computer Science Unit 2 Best Practices
41

I have no idea, but will see after I teach the unit for the first time

42

Constantly evaluating them and given them hints as to whether they are ho or cold.

43

Often making it a competitions with a prize, such as candy or extra credit points, keeps them focused on finding the correct or best solution to the problem.

44

My lesson will be on the following: Linear & Binary Search Algorithms

45

For my students, it will be a major task just to get them to understand the tower building problem. The video on searching the phone book might also be helpful.

46

My students tended to want to do bigger and better so for those groups I allowed them access to more legos to build bigger towers. They liked variables as well, different locations for example.

47

I could start out the lesson with the students explaining the steps in the problem-solving process or give them a list of the problem-solving process and have them provide details on each of the steps they follow. They will get in a competition with each other to see who can come up with the answer the faster. Furthermore, if someone comes up with a shorter time period to complete the tower, they will review and revise their approach to either come up with a shorter time than their peers or at least the same amount of time. My kids will love this assignment.

48

I posed it as a typical contractor bidding on a job and that I would go with the contractor that got the job done most efficiently.

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49

I just constantly kept on using the 4-steps whenever we work on problems so that they will see how the 4-steps process is used all the time. I wouldn’t accept their solutions to the problems if they did not the show 4-step process.

50

I will emphasis the problem solving stages. Comparing solutions with others students allow them to rethink their approach to problem solving that maximizes their solutions.

51

The students turned it into a challenge by seeing you could solve the problem the fastest and correctly. Working in groups or pairs have helped to keep students engaged and focused on the problem solving lessons.

52

This was a very hard lesson for me to understand as the objectives and specifics of this lesson could have been stated more clearly. I will remember this in teaching this lesson with my students. Also, I will walk around the classroom and encourage the groups to try another strategy to solve the problem.

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53

Students were overly-focused on trying to find exceptions to the requirement that it takes a full week to stack one block on top of the other. I feel that even though I clarified directions from the vague ones provided, they would need even more direction. As a non-computer scientist, I struggle sometimes giving context and explaining that “this is how computers need to process” and that they cannot operate as a human. Students can be kept focused in the process by being challenged to describe the process more so than just find an answer.

54

I agree making it relevant will help a lot

55

The students are getting more and more comfortable with being wrong. At the beginning of the year students were more hesitant to share out for fear that they didn’t have the right answer. They have learned that everyone’s input is good because having someone discover what doesn’t work shortens the next persons journey to solution.

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56

Tip: Provide additional examples for the binary search activity in ECS because students struggle to understand this activity and how it connects to binary search.

Goal:

  • Students construct their own understanding of the binary search algorithm.
    • While this is the purpose of the binary tower activity, it may not work on it’s own so it’s important to have other resources to try.
Reason:
  • Binary search is a fundamental algorithm in computer science.
  • Students need to explore the binary search algorithm to see how and why it works before they use it to problem solve.

Action:

  • After students spend time solving the binary tower activity show the Santa’s Dirty Socks video, which explains this concept by starting with a large number of units and dividing it down until only one unit is left.
    • The engaging solution from this video may help students understand the binary algorithm and apply it to the tower lesson.
    • Ask students for other examples when they would use the binary search algorithm.
  • Important: Rename the “Trump Tower” in the lesson to “CS Tower.”
    • Donald Trump has become too political as a result of the 2016 elections and distracts from the important work of the problem.

Additional Resources:

  • Try to quickly guess a number between 1 and 1000 using binary search as an additional activity.
    • This can be used before the binary tower activity, in place of it, or after it. It provides an opportunity for students to discover the use of the binary search algorithm for this divide-and-conquer strategy to find a single number.
    • Here is how it is done:
      • Get students into groups. Have one student in each group secretly pick a number and have the rest of the group guess the number using yes and no questions.
      • Groups must count how many guesses it took them to get the right number.
      • After groups spend a few minutes guessing their number, hold a class discussion to share the strategies the group used to discover the correct number.
  • This video shows a visual explanation on how to use the binary search algorithm to find a name in a phonebook.
    • This example is from Harvard’s CS50 course and is a direct lesson in this ECS activity.
      • Activity ends at the 25 min mark.
  • Here is a great explanation of binary search and how it is used in computer science from Khan Academy.
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57

Communication throughout the process and checking in with each group helps keep them focused. Keeping them from giving up is a challenge. Groups and the support they offer each other contributes to the problem solving process. Others points of view…always valuable.

58

Partners were Renee Smith, Kathy Krohnert,

I have used this lesson borrowed from CS Unplugged. This is a great activity to introduce binary to students. I teach High School and they loved it better than trying to show on the board, etc. Students use the cards and show the binary number as I, the teacher, give them a new decimal number to convert. A fun activity. Pull out the cards a few days later and give them more numbers to convert for 5 minutes or so. They like the challenge to see who gets the conversion first.

Binary from CS Unplugged.pdf (504.5 KB)

59

I put my students into groups and had them “compete” against each other to see if they can find the correct answer. They had to explain their process when they figured out the problem.

60

I got lucky because I have a group that loves to play with legos! I had them get into groups and compete against each other to see who could answer CORRECTLY first.