Our school board is actually thinking about something similiar. No child will receive a grade less than a 50%. They are not allowing retest on grades below a 75 though. The reasoning behind this is for children who need encouragement. For example if there are only 5 grades in a marking period that would mean, one would need a total of 450 points to receive a 90%. If a child completely bombs test, etc. and receives a 0, now there other 4 grades even if they received a 100 on each of them would only allow them to get 400 points which would now average to an 80%, instead of if you had given them a 50% which would still allow them to average a 90%. Once an older child is able to figure out this averaging, they can quickly lose hope if they know an A, or whatever grade they are striving for is no longer within their reach.
The other reasoning is that a child who at least tries an assignment should not be penalized in receiving a 0 the same as a child who does not even attempt an assignment.
Not to justify it, just to explain the reasoning as it was explained to me.
