Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 166 · 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 is needed for the secret lemon message? (a) a magnet (b) yeast (c) a small bowl (d) turmeric powder
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) False (b) True
3. 3.⚖️ 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
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the same paper
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
6. 6.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
7. 7.True or false: putting the iron away is a job a child can do. (a) True (b) False
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) a small bowl (d) lemon juice
9. 9.⚖️ 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) True (b) False
10. 10.True or false: yeast is needed for the secret lemon message. (a) True (b) False
11. 11.⚖️ 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
12. 12.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) an adult with an iron (d) a small bowl
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) lemon juice (d) a small bowl
15. 15.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
16. 16.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
17. 17.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) turmeric powder
19. 19.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
20. 20.🍋 Which of these steps is a job a child can do? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) putting the iron away
21. 21.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
23. 23.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
24. 24.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
27. 27.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) putting the iron away
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
29. 29.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
30. 30.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) it gets darker (d) the paper floats
31. 31.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) plugging in the iron
32. 32.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) letting the paper dry (d) cutting the lemon
33. 33.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
34. 34.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) an adult with an iron (d) a cotton bud
36. 36.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
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 of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) writing the message (d) putting the iron away
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a battery cell (d) a cotton bud
40. 40.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a cotton bud (c) a balloon (d) a magnet

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