Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 515 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) white paper (d) lemon juice
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) how dark the writing is (d) the kind of juice
3. 3.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) dipping the cotton bud (d) reading the message
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a balloon (d) a magnet
5. 5.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a small bowl (d) a cotton bud
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
8. 8.True or false: cutting the lemon is a job a child can do. (a) True (b) False
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) how dark the writing is
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
12. 12.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
13. 13.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
14. 14.True or false: plugging in the iron is a job a child can do. (a) True (b) False
15. 15.True or false: ironing the paper is a job a child can do. (a) True (b) False
16. 16.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) putting the iron away (d) cutting the lemon
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
18. 18.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
19. 19.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
21. 21.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
22. 22.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) letting the paper dry
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) ironing the paper (d) plugging in the iron
24. 24.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
25. 25.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
26. 26.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
28. 28.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) white paper (d) a mirror
30. 30.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) a small bowl (d) a balloon
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a cotton bud (d) a small bowl
33. 33.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
34. 34.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
35. 35.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
36. 36.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) reading the message
39. 39.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
40. 40.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) writing the message (d) plugging in the iron

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