Be sure that all students understand the goals of the challenge before beginning, and that they are formulating evidence-based strategies for completing the challenge. After students view the video, have a whole-class discussion about the challenge using students' answers to the questions as the basis. 

Remind students that they can apply everything they have learned so far in the course to complete the challenge. They can use journal entries from previous units, like path planning, to support their claims or to help them form and discuss initial strategies.

Remind students of challenge expectations at the start. 

• Students will engage in the same process of driving, coding, and exploring from the lessons to complete the unit challenge. 
• Brainstorm with students how they will make sure that each group member contributes to both collaborative strategy development as well as coding and iteration.
• Remind students that iteration will be a big part of this challenge. Encourage them to document the changes they make so they can explain how they arrived at their strategy when they share it with the class later.

Distribute the Step 2 task card (Google / .docx / .pdf) to students to guide them through their collaborative strategy development. Allow extra time for driving, to ensure that all students in a group get a chance to demonstrate their path plans and strategy ideas before choosing one to move forward with.

As you circulate through the room, check in with each group to see how they are sharing and collaborating on a challenge strategy. Ask questions like: 

• What have you tried so far? Was it successful? Why or why not? 
• What is one thing you think you can improve on to make your collaborative strategy better than an individual one? Why do you think that will help?
• How is your group collaborating to develop a strategy or a planed path for your project?

Ensure all groups can explain their strategy to you before moving on to coding their projects in Step 3. Give a signal to the class to let them know when it is nearing time to wrap up and move on to the next step. Remind them that they can return to driving at any point to help them complete the challenge.

Distribute the Step 3 task card (Google / .docx / .pdf) to students to guide them through collaborative coding and iterating to complete the challenge. 

Circulate around the room as students are coding, and engage them in conversations about their process and progress. Ask questions like: 

• How many barrels have you moved around so far? What is your next step? How is your documentation helping you to effectively build and test your project?
• What challenges are you facing as you create your project? How are you solving those problems? 
• How is your group collaborating to create your project together?

Students can move onto Step 4 once they have completed an initial project to complete the task. They should move freely and frequently between driving and coding to improve their projects. Encourage students to think about the reasoning behind their iterative changes as they work. Ask questions like: 

• What about your strategy are you trying to improve? What is your goal for this iteration? 
• Why do you think your idea will be successful? How will you know? 
• How are you going to work together to implement that change? What role will each group member play in this iteration?

In a unit challenge, you can determine when it is time to end the challenge and transition students into sharing their learning. Once you feel that all groups have had time to complete the challenge effectively and iteratively, wrap up the challenge phase and move on to strategy sharing.

Once everyone has completed the challenge, come together for a whole-class strategy sharing session and discussion. This is an opportunity to highlight the interplay of driving and coding to solve the challenge, and for students to engage in scientific discourse to make a claim and defend their claim with evidence. The goal of this section is to give students an opportunity to share their success, and to engage in discourse about the different strategies and approaches. 

The discussion should center around the final bullet – Do you think your strategy was the best way to complete the challenge? Why or why not? By the end of the discussion, the class should have consensus on what the best approach means to them. 

• Begin with one group sharing their strategy or demonstrating their project for the class, and presenting their answers to the questions. 
• Other groups then respond to what was shared, using their strategy for the project and journal documentation as evidence to support their claim. 
• Encourage students to think more deeply about what the ‘best’ means in this challenge. Time is an important factor, but what other criteria should be considered? Why? If two projects had the same time, what would the tiebreaker be?

Remind students about classroom expectations for respectful discourse and encourage them to agree or disagree with evidence and not judgment.

Remember, the purpose of Reflect and Share is to guide students to: 

• Evaluate their progress toward each learning target, using evidence from their journals to support their claims.
• Guide the class as a whole to converge their thinking around the unit understandings. 
• Relate their learning to real-world applications.

First, students will complete the sentences to reflect on their progress toward each of their learning targets.

Next, engage students in a whole-class discussion by inviting students to share what they wrote in their journals. Guide students towards shared conclusions about each of the unit understandings, using prompts like: 

• Which explanation best matches the observations we collected throughout the unit? How do we know? 
• Is there evidence that makes one explanation stronger than the others? Why? 
• Can we agree on one explanation based on our combined evidence and discussions throughout the unit? Why or why not?

Once you have guided students' thinking to converge around the unit understandings, you may want to create or add to class artifacts that display the class's shared understandings for students to refer to moving forward. 

Finally, students should relate their learning to the real-world connections they brainstormed at the beginning of the unit. Guide the discussion with questions like: 

• What connections can you make between our learning today and the experiences you shared earlier from outside the classroom? How does what you learned apply to real-world scenarios? (Student answers will vary depending on their relevant experience.)
• How do these real-world scenarios relate to precision? What would happen if that example was not as precise?