Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 552 · 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.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) writing the message
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
4. 4.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
6. 6.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) dipping the cotton bud
7. 7.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
9. 9.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
10. 10.True or false: reading the message is a job for an adult. (a) True (b) False
11. 11.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) yeast
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a battery cell (c) white paper (d) an adult with an iron
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a battery cell (d) an adult with an iron
15. 15.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
16. 16.True or false: plugging in the iron is a job a child can do. (a) False (b) True
17. 17.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) yeast (d) a battery cell
18. 18.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
19. 19.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
20. 20.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) reading the message
21. 21.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
22. 22.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
24. 24.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
25. 25.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud
26. 26.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) writing the message (d) reading the message
27. 27.True or false: plugging in the iron is a job for an adult. (a) False (b) True
28. 28.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) writing the message (d) dipping the cotton bud
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a small bowl (d) a balloon
30. 30.⚖️ 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 ironing time (c) the kind of juice (d) the same paper
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
33. 33.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) a battery cell (d) a mirror
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
35. 35.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
36. 36.True or false: ironing the paper is a job for an adult. (a) False (b) True
37. 37.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: letting the paper dry is a job a child can do. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) how dark the writing is (d) the same paper
40. 40.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud

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