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The array model (above) uses double sided counters. Yellow positive and red negative. See integers for more details.
Compare with algebra tiles (or see below)
All representations for 2D Dienes blocks (base 10) use the same colours as algebra tiles for ones, x and x squared including red tiles for negatives.
Multiplication of two linear factors is modelled as an area using dynamic algebra tiles.
x is variable in all models. See the model below to link the area model with the graphical representation.
(x + a)(x + b)(x + c)
Completing the square model allows students to see the structure of the general form of
x2+bx + c = (x+b/2)2 -b/22 + c
b/22 and -b/22 make a zero pair.
Change a and b to change the size of the squares. The a+b and a-b labels are draggable to allow students to place them by the correct side.
Fractions, decimals and percentages are represented by a 100 grid, decimal number line, percentage number line and bar model. Instruction video link
Bar model, double number line and ratio table. Instruction video link.
Base blocks allow students to make the link between Dienes blocks (base 10) and algebra tiles (base x) by exposing the mathematical structure of the place value of the base system.
Compare the expressions with the dynamic algebra tile representations using the variable sliders to change x.
This representation models the x and 1 algebra tiles. The green tile, x, is a variable and can be changed with the slider under the x axis.
These dynamic Cuisenaire rods show the first 5 terms and the nth of linear sequences of the form mn+c. Connections can be make to graphical representations and y=mx+c.
See Trigonometry with unit circle for examples
See Trigonometry for further examples
Arithmetic and Algebra in Early Mathematics Education Adapted from D.W. Carraher et al. (2006).
This representation models stretching a springs and compares this with a table and graph of two points on the spring. See https://www.ncetm.org.uk/media/mqfp3xb3/ncetm_ks3_cc_3_1.pdf page 9