Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 939 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a magnet
4. 4.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) ironing the paper (d) letting the paper dry
5. 5.True or false: plugging in the iron is a job for an adult. (a) True (b) False
6. 6.⚖️ 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
7. 7.🍋 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
8. 8.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
9. 9.🍋 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
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) a magnet (d) a mirror
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) white paper (d) a cotton bud
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
14. 14.⚖️ 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
15. 15.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) putting the iron away (d) reading the message
16. 16.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
17. 17.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
18. 18.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
19. 19.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
20. 20.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
21. 21.⚖️ 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) how dark the writing is (c) the ironing time (d) the iron setting
22. 22.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
23. 23.⚖️ 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
24. 24.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) the same paper (d) the same cotton bud
26. 26.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
27. 27.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) cutting the lemon
28. 28.True or false: yeast is needed for the secret lemon message. (a) False (b) True
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) white paper (d) an adult with an iron
30. 30.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) plugging in the iron
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
33. 33.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) a battery cell
37. 37.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
38. 38.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: letting the paper dry is a job a child can do. (a) False (b) True
40. 40.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) ironing the paper

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