Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 395 · 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) an adult with an iron (c) yeast (d) lemon juice
2. 2.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a small bowl
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
6. 6.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
7. 7.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
8. 8.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) cutting the lemon (d) dipping the cotton bud
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a battery cell (d) a small bowl
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the kind of juice (d) how dark the writing is
11. 11.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
13. 13.⚖️ 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) True (b) False
14. 14.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
15. 15.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
16. 16.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
18. 18.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) physical (d) musical
19. 19.True or false: yeast is needed for the secret lemon message. (a) False (b) True
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a small bowl (d) an adult with an iron
21. 21.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
22. 22.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
23. 23.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
24. 24.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) a mirror
26. 26.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
28. 28.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a battery cell (d) lemon juice
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
34. 34.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
36. 36.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) cutting the lemon (d) putting the iron away
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) white paper (c) a mirror (d) a battery cell
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) turmeric powder (d) a battery cell
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) white paper (d) a magnet

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