Improve support for student data collection (volume, sink/float)

[arouinfar]

We demoed/discussed Density PhET-iO with a potential partner, and some ideas emerged from the conversation. Let's consider these ideas when work resumes on Buoyancy or when Density 1.2 becomes a priority (whichever comes first).

There isn't a good way for clients to collect volume data from a student's measurement. To measure the volume, students need to submerge the block in the pool.

@kathy-phet said on Slack:

The pedagogical conversation made think about some useful derived properties: the categorical sink/float/neutral was interesting and the volume submerged data was interesting, so you could plot volume submerged (or volume displaced) vs block volume, and see that it is linear (with different slopes for different materials).

Here are some ideas I can think of:

• Create a new derived property that tracks if a block sinks, floats, or is neutrally buoyant (compare ρ_block and ρ_liquid).
• Instrument the pool's volume indicator so clients can access the displayed value. Instrument its visibleProperty so clients can hide it to support predictions.
• Create a derived property to track the portion of the block's volume that is submerged. I'm not sure if this should be a static number based on the relative density of the block and liquid or if we would want to represent the amount of volume currently submerged (like when a student holds a floating block underwater), or if we want separate properties for both.

[zepumph]

As we begin working on Buoyancy again, I'll note this issue for https://github.com/phetsims/buoyancy/issues/51

[AgustinVallejo]

@DianaTavares do you feel we should do anything regarding this for the buoyancy publication?

[DianaTavares]

This is a PhET-iO, a potential partner request, and I really find it useful! Then I said, yes!

“Volume submerged” is also described here as a necessity, as well as in the teachers' feedback. I know that we discussed this in design meeting 8Feb24, and the decision was "not to display it" because KP said it is a nice exercise for students to discover/calculate it, but if it will be included in the PhET-iO, I think can be something to add in the preference to let teachers decide to show it or not.

I will bring this discussion to the next design meeting.

[DianaTavares]

Yes, considered this when Buoyancy go to PhET-iO design (or update for Density). This will not be included in the Buoyancy publication simulation (discussion in design meeting Feb 8, 2023).

MK: numerical vs categorical? It is not a requirement for a client at this moment. Numerical for now. KP is going to ask this client if there are more ideas about data related to this simulation.

[zepumph]

In the mean time, we feel that it would be valuable to include a derivedProperty for the volume submerged data. I'll see about adding that.

@kathy-phet and @arouinfar will report back from our client to see if there were any others that were important.

[zepumph]

• [x] @AgustinVallejo. In this issue, we want the derivedProperty you created to be PhET-iO instrumented. I believe likely the best spot for that is somewhere in the model. Should we revisit moving that to Mass.ts? Your work was being done over in https://github.com/phetsims/buoyancy/issues/112.

[zepumph]

• [x] Also over in https://github.com/phetsims/buoyancy/issues/113 for the fluid displaced panel, we moved the water level Property to a more central spot. I made a TODO there about instrumenting it for this issue.

[AgustinVallejo]

Should we revisit moving that to Mass.ts?

@zepumph In the above commit I created a property on Mass which is updated via the model in the addPostStepListener function. So far it seems to be working correctly, and it's Tandem.OPT_OUT, it'd be good to talk about this before instrumenting.

[zepumph]

Excellent thanks. I'll mark this for work during PhET-iO review.

[zepumph]

• [x] Instrument buoyancy.compareScreen.model.pool.fluidLevelVolumeProperty. Done!
• [x] Instrument the submergedMassFractionProperty
• [x] Rename submergedMassFractionProperty-> percentSubmergedProperty, range [0,100], and other updates to accommodate the value change. Units would be '%'.

[samreid]

The client can check whether a block will sink or float by comparing the densities, perhaps document this in examples.md?

(await phetioClient.invokeAsync( 'buoyancy.compareScreen.model.blockSets.sameMass.block1A.materialProperty', 'getValue' )).density;
await phetioClient.invokeAsync('buoyancy.compareScreen.model.pool.fluid.densityProperty','getValue')