Wednesday, January 21, 2015

When is a rectangle an equilateral triangle?

As posted on ...

Diagonal of a rectangle has length 6 and makes a 30° angle with a side.
(a) Area of rectangle=?
(b) If diagonal has length d, area=?


(1) A moderate difficulty problem for SATs? Appropriate or too hard for a PARCC assessment with both parts?

(2) Should diagram be given or is drawing part of what's being assessed?

(3) Will some students recognize that the expression in terms of 'd' is the formula for the area of an equilateral triangle of side length d? If no one does then is it our responsibility to model and facilitate "connection-making"? Uh, yes ...

More interestingly, will some students realize that the rectangle divides into two 30-60-90 triangles which can be rearranged to form an equilateral triangle? Hence, the title of this post!

If we create this kind of environment in our classes it may happen. I think we're all conditioned to thinking that's only for the top honors groups,  and only for a few students. But, for me, helping ALL children discover and uncover the beauty of mathematics was my raison d'ĂȘtre for teaching. Idealistic perhaps but when that is lost, what's left?

Monday, January 12, 2015

How one 2nd grader knows his 7 Times Table!

As posted on twitter @dmarain today...

Question to 2nd grader: 7×6
How did you know that?
Easy --- 6 touchdowns! I know all my 7's!

1) So do you think this is about a real 7-yr old?

2) Would this be useful to many or just for girls/boys who watch a lot of football? OR

Is there a bigger issue here re the individual ways in which children learn? I think there are some HUGE implications here for teaching/learning in the Common Core and beyond...

3) All these "strategies" turning you off? Yearning for the good old days -- having children write their facts 10 times each or flash cards and memorization?

I have mixed emotions since I'm probably older than most of my readers but the anecdote above is real and it did work for this particular child! Further the child said, "I know some of my sixes too!" Missed PATs?? Maybe field goals will help with the 3s!!

Your thoughts?

Friday, January 9, 2015

Implement The Core: Quadratic Function SAT-Type Assessment

As posted on Twitter @dmarain...

The graph of f(x)=-(x-k)^2+h has one x-int and a y-int=-16. Coordinates of all possible vertices? Sketch graph(s).


(1) How do you feel about the "h,k switch" on an assessment? Would you revise it or leave it alone?
(2) Level of difficulty here? How do you think your students would perform? Let me know if you use it!
(3) Are you finding more of these types of questions in current texts? If not, what resources do you use to raise the bar?
(4) What if the question had asked for the PRODUCT of all possible x-intercepts? Better question for standardized assessments? Since the answer to this revised question is -16 do you think some of your students would ask if that's a coincidence? Why not ask them to check that -- Then GENERALIZE!

Thursday, January 8, 2015

BREAK THE CODE: 12-91-1305

As tweeted  on Twitter @dmarain today:

Break the code:12-91-1305
Then multiply these #'s by 4/3...
And you'll get my OBJective here!

Use contact form in sidebar to send me your answer/thoughts or leave a "hint" or question in Comments!