This lesson was a great “hook” for our color images lesson next. Some students accidentally found how to make colors when setting their “bits per pixel” which was interesting for them to play around with and led to a lot of other questions - perfect for tomorrow!
As a whole this lesson felt short for my group. I think tomorrow (color images) could go quite long. I almost wish I would have started talking about Hex a bit, but my students were still pretty engaged with the simulator - they made multiple images or started looking at color a bit.
I know that this first unit is supposed to be somewhat centered on abstraction but I feel weird not having explicitly discussed that with my students. I noticed that in lesson 17 they suggest a mini lecture but I wish my students were looking for abstraction all along. For this reason, today I talked about abstraction and asked students to consider where we have used it thus far and then also look at it in today’s lesson. Was there a reason for not discussing abstraction until the end?
This is a good move katie - talking about abstraction.
It turns out that showing the bits-per-pixel slider in this lesson was a bug. It shouldn’t have been there. It’s been fixed now, but you made some hay out of it it seems like.
The next lesson - color images - does go longer. WARNING: kids can get really into the personal favicon assignment (a good thing) so you might want to time-cap it to give them some constraints.
The videos that explain the color version of the tool do get into using hex as a more efficient way to express 4-bit chunks, since encoding pixels in binary with color…the number of bits starts to get really big really fast. I think using encoding images as the hook for hex works well.
Its one of those weeks and I’m doing my prep last minute and over tired and was hoping to lean on the lesson plan more than I sometimes do. I notice that the lesson plan doesn’t give me a suggestion of where in the lesson to show the video. I think it makes sense at the transition from paper to the Pixilation Widget.
A few fixes need to be made in L15 Stage 5 For Teachers Only
A: 65,041 bits
Explanation:
1.The max image size is 255 * 255 = 60,025should be 65,025 (width and height can only be expressed with 8 bits each so that’s 255 for each).
2.Since in this image there is one bit per pixel that means there are 255 * 255 = 60,025 bits of image data
3.However, the image file also must contain the 16 bits of width and height metadata, which are 8 bits each.
4.So the toal is: width * height + metadata = 255 * 255 + 16 = 65,041.
In the Extension activity of magnifying an image by a factor of 2
If it’s originally a 5 x 5 grid does it become a 10 x 10 grid but doesn’t that magnify by a factor of 4
or does it become a total of 50 grids but then that’s not a square any more
I can see where both arguments will be made by my students and i’m not sure which is correct and how to proceed and i definitely want to use this extension
So, yes we are assuming uniform scaling. “doubling” the size of the image means doubling BOTH the height and the width dimensions. 5x7 —> 10x14 and so on.
Therefore “doubling” a 5x5 image means making it 10x10.
5x5 = 25 pixels
10x10 = 100 pixels
25*4 = 100 therefore the new image is 4 times bigger.
However there is an intended nuance of language here. That “doubling” the image means 4 times as many pixels. Actually making twice as many pixels is hard/weird/impossible because to do that you’d have to alter the original image in odd ways.
For example to make that 5x5 image actually be twice as many pixels you’d have to somehow make the image have sides of √50 (which is not a rational number).