When you open Scratch, the screen is divided into three sections. On the far left, you will find the different commands we can use to instruct Scratch. In the middle, we have an open Script pane where our commands are added and linked. And on the far right, we see Scratch in the middle of the stage, waiting for our instructions.
Drag the "move (10) steps" block to the scripts portion of the screen and drop it. Then double click on this block. You should see Scratch start to move. Every time you double-click, the instruction will be executed and Scratch should react accordingly.
Next, drag over the "turn right (15) degrees" block. As before, when double-clikced, Scratch will react. You can link these two block together by placing one near enough to the other such that a white line will appear between them. When the block is released, the two blocks will be joined. And when double-clicked, they will be executed together, first the one on the top, then the one on the bottom.
If you want to change how far Scratch moves or turns, click inside the white bubble where the number is found, and then type in your new number.
Task: With one mouse click, move Scratch to the edge of the screen, then have her move in a square.
Task Have Scratch draw your initials on the screen with one mouse click. As you test out your command blocks, you might find the "clear" button helpful.
Find the "repeat (10)" block and drag it to your script screen. Any blocks placed inside the "repeat" block with be executed as many times as are specified, and the number can be changed by clicking on it and typing in a new one.
Task: Use the repeat block to have Scratch draw a square. Alter this block to have her draw an octagon.
Task: What is the general formula for the angle given the number of sides?
To plug this formula into Scratch, we need two items, Variables and Numbers. Under the Variables tab you will see a button called "Make a Variable". Click this and name the variable "sides". Create another variable called "angle".
We now have new blocks to use in our programs. First, drag over a "set ___ to 0" block, add it to the top of your drawing segment. Select "angle" as the variable, and type 72 into the block. Next, drag over the "angle" block, and place it in the "turn right ___ degrees" block. We've now separated and generalized this number, so whatever we set the angle variable to, the "turn right ___ degrees" block will use that same number.
One more step, and we can have the angle depend on the number of sides. Drag over a "set ___ to 0" block, select sides, and type 5 into the block. Add it to the top before the "set angle to 72" block.
Now, select the Numbers tab. You'll find at the top your common mathematical operators, +, -, *, /, with a place on the left and the right. Drag over the division block and place it inside the "set angle to ___" block. Use the formula you devised up above to relate angle and the number of sides, adding blocks and numbers as necessary.
To earn a C, write a program to draw a spiral.
To earn a B, write a program to draw a pie with 5 pieces as shown below.
To earn an A, write a program to draw a pie with n pieces, using variables and repetition blocks.
To earn a 100, write a program to draw a flower when given the number of petals.