("G" is Grayson Wheatley; "S" is the student.)
G – Can you write 2, 3 decimals between 6 and 3/10. If you would write 6 and 3/10 then and over here 6 and 5/10. Can you write 3 decimal numbers between those that are larger than this and less than this?
S – 6.4, 6.45, 6.468.
G – So you could throw in 3 digits. OK. Great. What would I have to add to 17 1/2 (write that down, if you like) 17 1/2 to get 20 1/4.
S – 20 and 1/4.
G – Yes. See you have written this as a decimal. OK.
S – So what was your question?
G – My question was, what would I have to add to 17 1/2 to get 20 1/4 ?
S – If I do 20 divided by…20 minus 17…5. OK, I would do 17 minus 5 is 7, 2, 1. 12.5. I’ll go back, check 17.5 and 12.75.
G – What do you think? What did you get when you added those?
S – I have 10 too much.
G – Uh huh. So what would the answer be if you have 10 too much?
S – 2.75. I forgot to cross out the 2 from the 1.
G – Uh huh, so you just want to write that over here?
S – It would be 20.25 minus 17.5 and that would be 2.75.
G – OK, and just how you did it. Now if we think in fractions now. If we are at 17 1/2 , what would we have to add to get 20? Just mentally what would we have to add to get from 171/2 to get up to 20?
S – 3 1/2.
G – Let’s see….
S – 2 1/2.
G – 2 1/2, OK how much more do we have to add to get 20 1/4?
S – 1/4, so it will be 2 3/4 to get….
G – So 2 3/4 and you wrote 2 3/4 in decimal form. Makes good sense to me.