Unit 2 Lab 3: Tools and Techniques, Page 1

MF: See also Game of tag
BH: How about some experience before formality? Have them make scripts like forever (go to mouse pos, if x>0 set pen color to red else set ...blue).
GH Feedback 10/20/15: Why has there been no work to save lately?
GH Feedback on U2 that seems to relate to this more: The "or" and "and" blocks aren't the most intuitive, so it might be useful to have a description and use a true/false chart of some sort.
GH Feedback 11/2/15: I would use the word Predict instead of the word determine. Great page though!
- I almost just went ahead and did this, and then I wondered about the use of the word "predict" on a page about "predicates." --MF

From Observation Notes Analysis:

U2L3p1: "In problem 1, what they’re mostly struggling with is abstraction. The only "math" (in the trad sense of facts or calculations) involved is deciding what size to make an individual cell of the n-by-n array, given n and some intended overall width. Nobody had any difficulty knowing what that calculation should be, but some did have difficulty sorting out where to use it."
U2L3p1: "In problems 2 and A, it’s easy to see them trying to invoke mathematical "things" they know that they know, but struggling to figure out what those ideas all mean. Many succeeded with a fully general solution—a function that took board size, n, and sprite coordinates and computed the cell number from that—and some did it in a way that had a useful substructure—independently computing the row and the column and then using those to compute the cell. But there were lots of ideas that led in unproductive directions, too. "

Try to evaluate these without using snap, and then check your answers by building the blocks.

Determine what each of these Boolean expressions will report (without using snap):
Determine what each of these Boolean expressions will report:

Now, you will create some more tools that you may use often, especially for complicated programming tasks.

Reopen your "U2L1-Predicates" file.
snap has a "greater than" operator (>), an "equal" operator (=), and a "less than" operator (<) built in, but doesn't have a "greater than or equal to" (>=) operator.

Build and test it well to make sure it does what you expect.
- When you type the block's title in the Make a block dialog, choose the hexagonal predicate block shape.
- To set the block's name >= between the two input slots, use the left plus sign in the Block Editor.
- You may find one or more of these Boolean operators helpful:
There are several correct ways to do this! As long as your block gives the right true and false answers, it's correct.

Is this on the AP? If not, do we need to teach this vocabulary?

Operators like a times b

that stand in between their two inputs are called infix operators. Operators like sqrt of

that stand before their inputs are called prefix operators. When we write n! to mean "n factorial," the "!" is a postfix operator—it comes after its input

Predicates and Logic