Number Grids

This set of grids is intended for use with younger or less able children. It contains simple grids with small numbers.

You must have My World installed on your machine in order to make use of the screens. The files on the disc are taken from a huge collection of thousands of similar screens, generated automatically on an Acorn computer. All My World files are basically Acorn Drawfiles - the PC version of My World can interpret Drawfiles, though in one or two minor respects My World runs more satisfactorily on Acorn machines.

These files are intended for use in whole-class or group activities in numeracy teaching. They are designed to be used by teachers, and to act as a focal point for class or group discussion. Successful whole-class teaching depends on the exercise of professional judgement by the teacher when deciding what questions to ask, how to phrase them, and which pupils to direct them at. The best questions are ones which are pitched at the threshold of children's competence, so that they are challenged by them but they can successfully answer them. No computer program can make accurate judgements of that sort, as the judgements depend in part on local and particular knowledge of individual children. These files can only be as effective as the user makes them.

**Note for Acorn users**

Before you can use these files you will need to:

open each directory in turn

choose 'Select All'

choose 'Selection'>'Set Type'

enter 'Drawfile'

**MSQ,*** *with directories for addition and
multiplication

Magic square grids. Numbers in the main part of the grid are the products or sums of
random numbers placed round the edges.

From the revealed numbers it is always possible to deduce the hidden numbers.

**Filenames**: the first digit denotes the size of the grid; the second
denotes the largest number in the range from which the edge numbers are chosen.

**Gridz**

A selection of number grids with all numbers hidden. Ask children to predict what
numbers are hidden.

**Filenames**: the first digit denotes the grid size; the second denotes the
number in the top left corner; the third denotes the interval between numbers. All grids
work sequentially from top left to bottom right.

**Ergo**

Similar to Gridz, but working on both axes, with different intervals on each.
Grids can run from top or bottom, left or right.

Colours are provided to enable you to use the grids as a team game if you wish (e.g. take
it in turns to predict the numbers under your colour).

**Numbloc**

Click on the green rectangle, and place it over the four numbers that sum to the value
in the green box, then do the same for the blue, etc. Solutions are always unique. You can
check by looking at the figures under the coloured boxes. What strategies can you use to
help you decide if a solution is plausible?

**Filenames**: first digit denotes grid size; next digits denote maximum
number size.

**Nos***
*The missing numbers are stacked, randomly, to the left of the grid. Decide where they
should go. Directory names indicate the percentage of numbers removed.

**NPuz**

The numbers at the bottom and right indicate the sum of each row, column or diagonal.
Reveal a few numbers - what else can you calculate? On a 3x3 grid, it's possible (though
not easy...) to deduce all the numbers if you remove one corner and two opposite middle
covers (e.g. a,f,h).

**Filenames** denote grid size then maximum values.

This set also includes two very simple *counting *screens, which are
self-explanatory.

ALL FILES AND PROGRAMS ARE COPYRIGHT BOB FOX.