After building the dice model and looking at the more complicated Nuclear decay model, students observe this model and the attached graphs. This model was built to show students that there can be a series of decays and that they can occur at various times.

The stocks are animated in the classroom version, and this adds to student understanding. After viewing it the first time, students wanted to adjust the graph so that there was only one scale on the left. They quickly discovered that this "hides" much of what is going on because of relative size. It is presented here with the multiple scale format.

 THE MODELS

[Diagram Level | Equations Level| Graphs ]

```Amt_Isotope_1(t) = Amt_Isotope_1(t - dt) + (- Decay_1) * dt
INIT Amt_Isotope_1 = Init_Amt_Isotope_1

Decay_1 = LOGN(2)*Amt_Isotope_1/Halflife_1
Amt_Isotope_2(t) = Amt_Isotope_2(t - dt) + (Decay_1 - Decay_2) * dt
INIT Amt_Isotope_2 = 0

Decay_2 = LOGN(2)*Amt_Isotope_2/Halflife_2
Amt_Isotope_3(t) = Amt_Isotope_3(t - dt) + (Decay_2 - Decay_3) * dt
INIT Amt_Isotope_3 = 0

Decay_3 = LOGN(2)*Amt_Isotope_3/Halflife_3
Amt_Isotope_4(t) = Amt_Isotope_4(t - dt) + (Decay_3) * dt
INIT Amt_Isotope_4 = 0

Halflife_1 = 50
Halflife_2 = 0.5
Halflife_3 = 2
Init_Amt_Isotope_1 = 1000