# Use sketch as matching game

**URL:** <https://cl.desmos.com/t/use-sketch-as-matching-game/518>\
**Category:** Questions\
**Tags:** sketch\
**Created:** [June 18, 2019, 5:28pm UTC](https://cl.desmos.com/t/use-sketch-as-matching-game/518 "2019-06-18T17:28:57Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Norman\_Hoppe](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/norman_hoppe/32/323_2.png) [@Norman\_Hoppe](https://cl.desmos.com/u/Norman_Hoppe)\
**Post date:** [June 18, 2019, 5:28pm UTC](https://cl.desmos.com/t/use-sketch-as-matching-game/518/1 "2019-06-18T17:28:57Z")

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Just starting with CL and have no idea how to pull a single number from a numberList. I have a graph of 2 boxes and want student to connect the 2 with a sketch. I assumed I would compare the y-values at a given x and see if they fall within the box.

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**Author:** ![sergeballif](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/sergeballif/32/231_2.png) [@sergeballif](https://cl.desmos.com/u/sergeballif)\
**Post date:** [June 25, 2019, 6:57am UTC](https://cl.desmos.com/t/use-sketch-as-matching-game/518/2 "2019-06-25T06:57:58Z")

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Welcome Norman,

You started off with a hard question. Are you saying that you want students to draw a line to connect two boxes in a Sketch component? That might get very tricky to check because of how crooked the lines might be. If so, you might be better off using a card sort or a graph with draggable points (something like [Desmos | Graphing Calculator](https://www.desmos.com/calculator/kygevtckxe)).

Here’s an activity that checks whether students have traced a figure that might give you some ideas about how to extract the values from a sketch component. [Challenge 17: Untraceable • Activity Builder by Desmos](https://teacher.desmos.com/activitybuilder/custom/5a8df6ac7e91a208c59c9517)  
I can give more specific details if you would like, but I’ll wait to see if I am even understanding what you are after first.

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<div class="post-metadata">

**Author:** ![Norman\_Hoppe](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/norman_hoppe/32/323_2.png) [@Norman\_Hoppe](https://cl.desmos.com/u/Norman_Hoppe)\
**Post date:** [June 25, 2019, 11:55pm UTC](https://cl.desmos.com/t/use-sketch-as-matching-game/518/3 "2019-06-25T23:55:08Z")

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Again, I’m just learning so as a practice I made 2 polygons (squares) and then have students draw a sketch connecting them. I was hoping to pull y values at specific x’s and compare them to the y values of my squares.

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<div class="post-metadata">

**Author:** ![sergeballif](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/sergeballif/32/231_2.png) [@sergeballif](https://cl.desmos.com/u/sergeballif)\
**Post date:** [June 26, 2019, 8:54pm UTC](https://cl.desmos.com/t/use-sketch-as-matching-game/518/4 "2019-06-26T20:54:47Z")

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I still have concerns that students might not draw their lines all the way to your boxes, which would make checking difficult.

You can pass a list `L` of y-values from a sketch `S` to a graph (where the checking will take place) at `x=0.1` using the code `numberList("L"): sketchYValues(S.sketch, 0.1)`. You could then check to see if a value in `L` is close to `7` using an inequality involving `min(|7-L|)`

Here is an activity that does something similar. It displays the x-values of each point that is half-way up the sketch (just as an illustration).[Sketch check • Activity Builder by Desmos](https://teacher.desmos.com/activitybuilder/custom/5d13d614841421120eb1775c)

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**Author:** ![SeanMaths4EAL](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/seanmaths4eal/32/289_2.png) [@SeanMaths4EAL](https://cl.desmos.com/u/SeanMaths4EAL)\
**Post date:** [June 29, 2019, 7:03am UTC](https://cl.desmos.com/t/use-sketch-as-matching-game/518/5 "2019-06-29T07:03:09Z")

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Might you not be better off using a graph and having them drag points connected by lines to the correct place. Then you can set the step value to ensure things click nicely into place.

Somewhat like I’ve done differently in screen 4 of this:

> **[The language of geometry • Activity Builder by Desmos](https://teacher.desmos.com/activitybuilder/custom/5cff5df811be2863fc2c203f)**
>
> by Sean Kelleher

It doesn’t check for correctness, but it easily could. The reason I don’t is because there is significant discussion about what is the best answer in a couple of cases.