Take another look at the sentence:
When Richie jammed the photocopier for the eighth time, Sharon, the administrative assistant, picked up a heavy stapler and __________ it at his head.
The sentence requires the past tense of throw, an irregular verb. Threw is the simple past form.
|Verb||Simple Present||Simple Past||Past Participle|
Throwed, the form you chose, is a spelling error. Before you continue, review the rules for irregular verbs.