The Good Oil (on Upside Down Words) Years 2 - 8

Summary The Swan & Sparrow research mentions making '...words such as OIL'. If you type the number 710 into a calculator and turn the machine upside down the screen reads OIL. That mindless exercise has little to do with achieving the objective of Calculating Changes, ie: enhancing children's number sense, but kids enjoy it none-the-less. The activity asks: Can we use this interest to devise a more worthwhile activity? and answers with a resounding Yes!. Happily too, the activity links mathematics and literacy. Materials One calculator per person One Poly Plug per pair Poly Plug Paper Crossword writing software can be useful

Procedure The activity Calculator Art shows us that every digit can be made using yellow plugs in the middle three columns of a Poly Plug red board. This is the way the calculator displays digits using tiny pixels on the screen. Ask each group to make a different Poly Plug digit and display the results on the floor. In this example zero is missing and the four is not quite correct. Two plugs in the 4 are not needed. Compare with the calculator screen to find which ones. Stand on one side and ask the class to say the digits they see. Now stand on the other side:

Content addition facts beyond 10 division equations: creating/solving exploring large numbers multiplication operations - whole number order of operations place value recording - calculator recording - written subtraction times tables using brackets

and ask the class to read off the letters they see.

• 9 is 6, but could be small B
• 8 could be capital B
• 7 could be capital L
• 6 is 9, but could be small G
• 5 is 5, but it could be capital S
• 4 (without the two unnecessary plugs) could be small H
• 3 could be capital E
• 2 is 2
• 1 could be small L or capital I
• 0 of course, could be capital O

• How many two letter words can you make?
• What is the longest word you can make?

• Even more challenging, what about a crossword puzzle made from upside down words. The clues would be sentences, each using one upside down word represented by a partner equation. The equation would be evaluated to discover the missing word.

Here is how one teacher turned this idea into a powerful learning experience.

I first ask the students to discover which digits make letters when the calculator is turned upside down. For example, zero reads as 'O' and four reads as 'h'. Then we make words that use only these letters. Beside each one we write the number which would have to be on the screen to show this word upside down. The next step is to create equations which equal this number/word.

I usually introduce this activity at the start of the year when we are making a display of all the different ways children from the many cultural backgrounds in my classroom say 'hello'. Then, beside all the languages from different countries, we display all the ways we can think of to say hello in 'mathematical language', eg:

0·3867 x 2 = hELLO

I am always amazed with the equations the children create.

Later in the year we use crossword software to write clues which have to be answered with calculator spelling. Examples are:

• 0·3867 x 2 mate. 'Ow yer goin'?
• Where's the 2 x 360 - 10. I want to cook chips.

The children form groups to invent the clues and enter them into the software so we finish up with a class book of puzzles. The fun is in working out other peoples' puzzles, but the number sense is in the creation of the equations to make the calculator words.

Sometimes children use a calculator from home that doesn't operate with the order of operations and that can cause some interesting discussions. Their clues might be correct on such a calculator, but not actually correct mathematics. For example, one of my students thought this clue:

• Mum asked me to peel the vegies, but 70 - 1 x 5 didn't know I was going out.

gave the answer 345 on the home calculator, which would be ShE, but the correct answer is 65 because multiplication comes before subtraction. Some simple calculators are programmed to use order of operations. Some are not. This caused a side step into discussing the convention for order of operations, use of brackets and features of one type of calculator compared to another.

Another Story

Debbie made a class book with page after page of the children's equations and words. These are only a small sample:

• 8,845 - 1,111 = 7,734 = hell
• 35,009 x 1 = 35,009 = goose

• 5,003 + 504 5,507

  = loss

• 300 + 40 + 5 = 345 = she
• 400 - 100 + 30 + 16 ÷ 2 = 338 = bee
• 9 x 7 + 2 x 300 = 663 = leg
• 1377 x 2 x 2 = 5508 = boss
• 150 x 2 + 90 ÷ 2 = 345 = she

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