Ethereum Smart Contracts — Interactive Micro‑Lab / offline, single‑file

Accounts

Active Caller (EOA)

Deploy Contract

Example

Deployed

How to Use

Pick an example and Deploy. Select a deployed instance.
Open the Interact tab to call a function. Provide inputs and optional msg.value.
Click Call. The transaction is executed and immediately committed as a new block.
Open the Chain tab → click a block to inspect header, inputs, receipts, and outputs.

Concepts reinforced

EOAs vs contracts, deployment, calldata & state, events/logs, gas intuition, CEI and reentrancy, and contract–to–contract calls.

Self‑Tests

Code

// Select or deploy a contract to view its code here.

Trace

Call Stack

Events

Selected Contract — Storage

Balances (ETH)

Blocks

#	Txs	Gas	Time

Click a block to inspect its header and contents.

Block Detail

— click a block to view header, inputs, receipts, and outputs —

Instructor Tips • prompts to use during the lab

Ask students to predict the next state change before executing a call.
Switch callers to show msg.sender authorization effects (e.g., Coin.mint).
Trigger the reentrancy attack on VulnerableVault, then repeat on SafeVault to contrast CEI.
Have students read emitted Events and explain how off‑chain indexers could react.
Discuss gas intuition: each operation adds a small “gas” count (rough proxy) shown in traces and per‑block totals.