Hi, never done this for a child minder, but do risk assessments for construction sites all the time.
The way we do it, risk is considered to be the "severity" of an event happening, times the likelhood of it happening.
Draw up a table
Call the columns "Event", then "Severity = 1", Severity = 2", Severity = 3; "Likelyhood = 1", "Likelyhood = 2" and "Likleyhood = 3".
In the first column, starting on the second line (ie below the headings i've just given), have a list of all the risks. Eg: "Falling in Pond", "Grazing knee" etc
In the next 3 columns put the whether it is 1 (low), "2" medium or "3" (high) severity scores - the severity of any possible injury. ie: No damage (1), first aid (2), hospital treatment (3).
In the next 3 columns, put the likelyhood "Unlikely (1)", "Possible (3)" and "Likely (3)".
In the final column, put the title "Overall Score". Then go through each "event" and tick a severity and a likely hood. Times their values together to get the final score. So if, for example, you think "grazing knee" has a high likely hood (ie 3) and a low severity (ie 1), then the overall score is 3 x 1 which is 3.
So the top most overall risk will be 3 x 3. so that would be really severe, and the lowest will be 1 x 1.
You need to decided what overall risk is unaccepatble - usually 4 or 5. Anything that reaches those levels you then either decide not to do, or put in mitigation actions (things to do to reduce the risk), and re-assess the risks.
Does that make sense? CAT me if not, and I'll send you an example.