Change the hidden numbers words

[catherinecarter]

1. 
   When the total is hidden, either in PhET-iO on screens 1, 2, 3, or in both the PhET brand and PhET-iO sum screen, the missing total will say, "some number" instead of "a number."

The reason for this is because if the user has one or both addends hidden, the sentence gets confusing if two of the numbers say the same thing.

2. When the second addend is hidden, it should say, "another number"

Summary

• When the total is hidden, replace this with, "some number"
• When the left addend is hidden, replace this with, "a number"
• When the right addend is hidden, replace this with, "another number"

That way, when all three are hidden, the sentence would read, "some number can be decomposed into a number and another number"