# What is the answer to #9 on my daughter's math homework? Third grade, still. **URL:** \ **Category:** Factual Questions\ **Created:** [May 14, 2018, 11:03pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169 "2018-05-14T23:03:44Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Mahaloth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mahaloth/32/1079_2.png) [@Mahaloth](https://boards.straightdope.com/u/Mahaloth)\ **Post date:** [May 14, 2018, 11:03pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/1 "2018-05-14T23:03:44Z")
Yep, us again. [You may remember me from February.](https://boards.straightdope.com/sdmb/showthread.php?t=849433) According to my daughter, every student got a re-do on this math assignment. It’s called “Patterns of Geometry”. [Check out the assignment here.](https://imgur.com/a/VwZxqZU) Take a look. Realize my wife and my daughter have re-done the work and the checks indicate wrong answers(originally wrong, not the re-do). No matter how much they count that grid in #5, they can’t get an answer that produces a good response for #9. We think the answer should be “all of them are divisible by 5”, but we can’t get it to work out. The top half with the triangles was a chore, the kind of thing I’d expect in a fun activity pack. The bottom is fine, but we can not work it out. If anyone is very mathy, feel free to check all the work. It’s not the grade(daughter is doing fine normally). It’s the principle of not letting this HW defeat us. ---
**Author:** ![Mithras](https://avatars.discourse-cdn.com/v4/letter/m/f04885/32.png) [@Mithras](https://boards.straightdope.com/u/Mithras)\ **Post date:** [May 14, 2018, 11:08pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/2 "2018-05-14T23:08:47Z")
The answers are 25, 16, 9, and 4. All square numbers because you’re counting squares within a square. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [May 14, 2018, 11:08pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/3 "2018-05-14T23:08:49Z")
25, 4, and 9 are all square numbers. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [May 14, 2018, 11:30pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/4 "2018-05-14T23:30:04Z")
> [@Mahaloth](#): > > The top half with the triangles was a chore, the kind of thing I’d expect in a fun activity pack. What answers did you eventually get? ---
**Author:** ![Mahaloth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mahaloth/32/1079_2.png) [@Mahaloth](https://boards.straightdope.com/u/Mahaloth)\ **Post date:** [May 14, 2018, 11:35pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/5 "2018-05-14T23:35:26Z")
> [@Robot\_Arm](#): > > What answers did you eventually get? The ones written in now on the sheet. Are we wrong? ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [May 14, 2018, 11:40pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/6 "2018-05-14T23:40:22Z")
> [@Mahaloth](#): > > The ones written in now on the sheet. Are we wrong? All the check marks are incorrect answers. That’s why she got a 1/10 and not a 9/10. ETA, should be 26,16,9,4, which as stated are all perfect squares. I’m not sure if that some how relates back to the beginning or just a happy/forced coincidence. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 14, 2018, 11:47pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/7 "2018-05-14T23:47:36Z")
> [@Mahaloth](#): > > The ones written in now on the sheet. Are we wrong? I count 36 triangles. ---
**Author:** ![Aspidistra](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspidistra/32/3894_2.png) [@Aspidistra](https://boards.straightdope.com/u/Aspidistra)\ **Post date:** [May 14, 2018, 11:48pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/8 "2018-05-14T23:48:12Z")
> [@Mahaloth](#): > > The ones written in now on the sheet. Are we wrong? Yes, I’m afraid so. They definitely all have to be square numbers (because of the geometry of the thing, in fact). Also, I believe the number of triangles should be 36 (4x4 for the outer layer, 3x4 for the middle, 2x4 for the inner) and it’s possible that the number she’s looking for for squares \*\*in \*\*the picture might be ‘3’, though I’d argue the point if I were marked wrong for 4. Another extension of the pattern would produce another 20 triangles (5 per corner, since the existing squares go 4-per, then 3-per, then 2-per) If ‘24’ and ‘8’ were the kid’s original answers for 1 and 4, then IMO the teacher should have marked her correct on 5, since she added up right. ---
**Author:** ![griffin1977](https://avatars.discourse-cdn.com/v4/letter/g/977dab/32.png) [@griffin1977](https://boards.straightdope.com/u/griffin1977)\ **Post date:** [May 14, 2018, 11:48pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/9 "2018-05-14T23:48:31Z")
Pretty awful ambiguous question IMO. It all boils down to whether you think this: [[Album] One square or two? ![](https://i.imgur.com/PlFWJy1.png?fb "One square or two?") ](https://imgur.com/a/p6PKXdQ) Is two rectangles or one. I would say both are valid answers, unless you explicitly define that in the question you are just rewarding making an arbitrary choice. Teaching that the correct answer that question is “there are two rectangles” is equally wrong IMO. It is just as valid to say that the shape is a single rectangle and two edges. ---
**Author:** ![Tired\_and\_Cranky](https://avatars.discourse-cdn.com/v4/letter/t/a87d85/32.png) [@Tired\_and\_Cranky](https://boards.straightdope.com/u/Tired_and_Cranky)\ **Post date:** [May 14, 2018, 11:52pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/10 "2018-05-14T23:52:55Z")
1. 36 2. 4 3. 9 4. 20 5. 56 6. 25 7. 16 8. 9, 4 9. They are all squares. 10. 55 I object to the grading on this. If the answer to 3 depends on the work for the first two, she should get credit for the right answer based on the wrong assumptions. ---
**Author:** ![MrFloppy](https://avatars.discourse-cdn.com/v4/letter/m/43a26b/32.png) [@MrFloppy](https://boards.straightdope.com/u/MrFloppy)\ **Post date:** [May 14, 2018, 11:59pm UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/11 "2018-05-14T23:59:23Z")
36 triangles 4 squares 36/4=9 20 (4 lots of 5) 36+20=56 16 (4x4) 9 (3x3) 4 (2x2) All square numbers 25+16+9+4+1=55 Good luck. ---
**Author:** ![Patx2](https://avatars.discourse-cdn.com/v4/letter/p/73ab20/32.png) [@Patx2](https://boards.straightdope.com/u/Patx2)\ **Post date:** [May 15, 2018, 12:04am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/12 "2018-05-15T00:04:17Z")
> [@beowulff](#): > > I count 36 triangles. I also got 36, and a headache. ---
**Author:** ![Aspidistra](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspidistra/32/3894_2.png) [@Aspidistra](https://boards.straightdope.com/u/Aspidistra)\ **Post date:** [May 15, 2018, 12:04am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/13 "2018-05-15T00:04:58Z")
> [@Tired\_and\_Cranky](#): > > I object to the grading on this. If the answer to 3 depends on the work for the first two, she should get credit for the right answer based on the wrong assumptions. yeah, me too, but sadly “she got a 1 and really deserves a 3” doesn’t play as well as “she got 4 but really deserves to pass”. Also, it looks like she’s fine on general arithmetic since she did the adding up correctly, but actually might be struggling in the geometry section. For instance, seeing that it’s symmetrical so that you only have to count a quarter of the triangles in the triangle picture, is a trick that would make her life a lot easier. Also, marking spots on a diagram with your pencil as you’re counting up things is a great trick. There are a lot of ways to approach these sorts of problems which would help her out here. Have they been doing geometry in class for long? ---
**Author:** ![Doug\_K](https://avatars.discourse-cdn.com/v4/letter/d/b5ac83/32.png) [@Doug\_K](https://boards.straightdope.com/u/Doug_K)\ **Post date:** [May 15, 2018, 12:06am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/14 "2018-05-15T00:06:38Z")
I found the worksheet and the answer key online. The answers are what MrFloppy said, except that for 9 their answer is “They are all products of numbers multiplied by themselves.”, which of course means the same thing. ---
**Author:** ![Mahaloth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mahaloth/32/1079_2.png) [@Mahaloth](https://boards.straightdope.com/u/Mahaloth)\ **Post date:** [May 15, 2018, 12:07am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/15 "2018-05-15T00:07:10Z")
> [@Aspidistra](#): > > Have they been doing geometry in class for long? No, and I suspect this might be in the category of “5th or 4th grade work she brought down.” It’s her first year teaching 3rd grade and occasionally, we get work we’re pretty sure was from 5th grade. My daughter had a research project that was kind of nuts for her age/experience. ---
**Author:** ![Patx2](https://avatars.discourse-cdn.com/v4/letter/p/73ab20/32.png) [@Patx2](https://boards.straightdope.com/u/Patx2)\ **Post date:** [May 15, 2018, 12:07am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/16 "2018-05-15T00:07:22Z")
> [@Tired\_and\_Cranky](#): > > 1. 36 > 2. 4 > 3. 9 > 4. 20 > 5. 56 > 6. 25 > 7. 16 > 8. 9, 4 > 9. They are all squares. > 10. 55 > > I object to the grading on this. If the answer to 3 depends on the work for the first two, she should get credit for the right answer based on the wrong assumptions. My daughter is in high school and these type of questions make her crazy. It’s stressful when one wrong answer screws up your answers to the next several problems especially, as you say, she’s basing her work off of a false assumption. The killer is when she actually shows the original work. ---
**Author:** ![Sunny\_Daze](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunny_daze/32/438_2.png) [@Sunny\_Daze](https://boards.straightdope.com/u/Sunny_Daze)\ **Post date:** [May 15, 2018, 12:11am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/17 "2018-05-15T00:11:42Z")
> [@Aspidistra](#): > > … and it’s possible that the number she’s looking for for squares \*\*in \*\*the picture might be ‘3’, though I’d argue the point if I were marked wrong for 4. This one tripped me up for a few minutes. They’re using the outer line to make the triangles work, but not for the squares. :rolleyes: **Mahaloth** come back, bring puzzles! This was fun. 😃 ETA: my parents were teachers. I was always told that if most of the class couldn’t do something, it wasn’t the students, it was the teacher. I’m glad they got a re-do. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [May 15, 2018, 12:29am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/18 "2018-05-15T00:29:28Z")
> [@Doug\_K](#): > > I found the worksheet and the answer key online. The answers are what MrFloppy said, except that for 9 their answer is “They are all products of numbers multiplied by themselves.”, which of course means the same thing. But the kid’s answer of 4 squares is clearly marked wrong on the sheet. And I agree it is the correct answer. As are the ones for the grid–though I would presume that they would be taught exactly how to count squares in such an arrangement. There is a specific way that mathematicians mean. If not defined beforehand, then many different answers are possible. (As a kid, my answer to the number of 2x2 squares would have been either 4 or 6 1/4–i.e. adding up the half squares and no overlaps.) ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [May 15, 2018, 12:36am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/19 "2018-05-15T00:36:01Z")
question #9 is a piece of shit. “what do you notice about all these numbers?” How can there be a wrong answer? “I didn’t notice anything.” are textbooks written by idiots? ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [May 15, 2018, 12:49am UTC](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169/20 "2018-05-15T00:49:37Z")
Regardless of the competence of textbook authors, recognizing patterns is a legitimate mathematical skill. The book may or may not be rubbish, but we cannot tell based on just the one question. [Next page](https://boards.straightdope.com/t/what-is-the-answer-to-9-on-my-daughters-math-homework-third-grade-still/814169.md?page=2)