The Life Starter
Sign up
Grade 3 · unit review

Review: Messages Travel through a Network

Using route A-R-B, send a three-part paper word with arrivals 3,1,2. Show restoration by number and explain what an absent acknowledgment can and cannot prove.

Download reviews and answer keys

Bring the unit skills together

Use these 4 new cases to check your reasoning. Choices are temporary and are not saved to an account, sent to staff or recorded as school grades. Download your current review choices before leaving or reloading.

Unit review questions
1. A sends a drawing for B. Map: A connects to R; R connects to B and C; D is isolated. Which route fits?
Need a hint?
  • Trace the connected links from the sender to the named destination.
  • A nearby device is not reachable if the required link is missing.
2. Packets arrive 3:T,1:H,2:A. Order by packet number. What message is restored?
Need a hint?
  • Order packet contents by their supplied sequence numbers, not by arrival order.
  • An early arrival is not necessarily the first part of the message.
3. Wanted map resource. Table: /a=animals; /p=plants; /m=maps; /r=rules. Which address fits?
Need a hint?
  • Match the requested resource to the address in the supplied lookup table.
  • A familiar-looking title does not prove the destination has the expected content.
4. Message 12 sent with no recorded response. Which specific sending-and-acknowledgment condition does this log show?
Need a hint?
  • Use the explicit acknowledgment as receipt evidence and keep missing responses uncertain.
  • Sending a message is different from confirming its receipt.

The download contains your current choices and any checked feedback. Keep the separate transfer-task work in your own document; downloading its instructions does not mark it complete.

Use the skills in a new task

Using route A-R-B, send a three-part paper word with arrivals 3,1,2. Show restoration by number and explain what an absent acknowledgment can and cannot prove.

Work on paper or in your own document. Explain the choices you made.

  • Use the pretend details in the task and name the rule you followed.
  • Show the steps or point to the detail that helped you choose.
  • Say one mistake to avoid or one thing this example cannot tell us.
  • Check your answer against the task. Change a part if you can show why it needs fixing.
Compare with a model response

Use message 21 and packet key 1:C, 2:A, 3:T. Sender A forwards each numbered part over link A→R, and router R forwards it over R→B to destination B. B receives 3:T, then 1:C, then 2:A. Sorting by sequence number gives 1:C, 2:A, 3:T and reconstructs CAT, rather than arrival text TCA. A matching acknowledgment for message 21 would confirm its stated receipt. Without a recorded acknowledgment, receipt remains unknown: delivery or its response may be delayed or lost. An acknowledgment for message 20 would not confirm message 21.

A different response can also meet the criteria. Compare the evidence and reasoning, rather than copying the wording.