Worked example · Expressive Arts · Year 4
DCF: Data and computational thinking → Problem-solving and modelling
A secure Year 4 response, annotated so you can see which success criterion each part meets. It is also the answer key. Key answers: every row makes 12; red 47, white 61, green 12, total 120 and 12 × 10 = 120; bugs: row 3 2G should be 2R, row 5 4W should be 3W, row 8 3W should be 4W.
| Row | Code | Total (must be 12) |
|---|---|---|
| 1 | 9W 2R 1W | 9 + 2 + 1 = 12 |
| 2 | 8W 4R | 8 + 4 = 12 |
| 3 | 8W 1R 1W 2R | 8 + 1 + 1 + 2 = 12 |
| 4 | 3W 1R 3W 5R | 3 + 1 + 3 + 5 = 12 |
| 5 | 2W 3R 1W 3R 3W | 2 + 3 + 1 + 3 + 3 = 12 |
| 6 | 1R 1W 7R 3W | 1 + 1 + 7 + 3 = 12 |
| 7 | 9R 3W | 9 + 3 = 12 |
| 8 | 1W 7R 4W | 1 + 7 + 4 = 12 |
| 9 | 2W 1R 4W 1R 4W | 2 + 1 + 4 + 1 + 4 = 12 |
| 10 | 12G | 12 = 12 |
Every total is shown as a number sentence, not just written as 12. Evidences criterion 2.
The dragon faces right with its eye in row 3 (the white square), a wing on its back, a tail at the left and grass along the bottom. Each row matches its code exactly. Evidences criterion 1.
| Colour | How many? | How I worked it out |
|---|---|---|
| Red | 47 | Red in each row: 2 + 4 + 3 + 6 + 6 + 8 + 9 + 7 + 2 = 47 |
| White | 61 | White in each row: 10 + 8 + 9 + 6 + 6 + 4 + 3 + 5 + 10 = 61 |
| Green | 12 | Row 10 is 12G |
| All squares | 120 | 47 + 61 + 12 = 120 |
Check: 12 × 10 = 120. It matches, so I have not missed any squares.
Another way to find white: 120 − 47 − 12 = 61.
Adds the counts row by row and uses multiplication by 10 as a check. A total that is not 120 tells the pupil to recount. Evidences criterion 3.
| Row | Gruff’s code | Total | Fixed code |
|---|---|---|---|
| 3 | 8W 1R 1W 2G | 8 + 1 + 1 + 2 = 12 | 8W 1R 1W 2R |
| 5 | 2W 3R 1W 3R 4W | 2 + 3 + 1 + 3 + 4 = 13 | 2W 3R 1W 3R 3W |
| 8 | 1W 7R 3W | 1 + 7 + 3 = 11 | 1W 7R 4W |
Adding up did not find the bug in row 3, because 8 + 1 + 1 + 2 still makes 12. I found it by comparing with the picture: the dragon’s nose is red, not green. You have to test the picture as well as check the numbers.
Uses the total to find two bugs and testing the output to find the third. Evidences criteria 2 and 4.
| Row | Loop | Number sentence |
|---|---|---|
| (a) | repeat 6 times [1R 1W] | 6 × 2 = 12 |
| (b) | repeat 3 times [3G 1W] | 3 × 4 = 12 |
| (c) | repeat 3 times [2R 2W] | 3 × 4 = 12 |
| (d) own loop | repeat 2 times [4G 2W] | 2 × 6 = 12 |
Each loop repeats a group that fits into 12 exactly, and the number sentence proves it. Other correct answers for (d): repeat 12 times [1G], repeat 4 times [1R 2W], repeat 3 times [2G 1R 1W]. Evidences criteria 2 and 5.
A tulip in red and green. Code: row 1 5W 2R 5W, row 2 4W 4R 4W, row 3 5W 2R 5W, row 4 6W 1G 5W, row 5 2W 2G 2W 1G 5W, row 6 4W 7G 1W. Every row makes 12. My partner drew it correctly first time.
The code is complete for every row and each row is checked. Testing it with a partner is how programmers test code. Evidences criteria 1 and 2.
Row 7, 9R 3W, cannot be a loop that repeats the same group, because 9 red and 3 white do not make a pattern that repeats. It is already as short as it can be.