Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 474 · 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 small bowl (b) lemon juice (c) an adult with an iron (d) a balloon
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
3. 3.⚖️ 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) False (b) True
4. 4.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
5. 5.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
8. 8.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
9. 9.⚖️ 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) False (b) True
10. 10.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
11. 11.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) reading the message
12. 12.⚖️ 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 ironing time (c) the kind of juice (d) the same cotton bud
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a magnet (d) lemon juice
15. 15.True or false: letting the paper dry is a job a child can do. (a) True (b) False
16. 16.True or false: letting the paper dry is a job for an adult. (a) True (b) False
17. 17.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
18. 18.⚖️ 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
19. 19.🧺 Do we need a cotton bud 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.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) writing the message
22. 22.True or false: yeast is needed for the secret lemon message. (a) False (b) True
23. 23.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
24. 24.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
25. 25.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) plugging in the iron (d) ironing the paper
26. 26.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a mirror (c) yeast (d) a battery cell
27. 27.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
28. 28.True or false: writing the message is a job for an adult. (a) False (b) True
29. 29.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) lemon juice (d) a mirror
30. 30.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) dipping the cotton bud (d) writing the message
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the iron setting (c) the ironing time (d) the same paper
32. 32.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) a balloon (d) a mirror
34. 34.True or false: writing the message is a job a child can do. (a) True (b) False
35. 35.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
37. 37.🧺 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 cotton bud (d) yeast
38. 38.True or false: ironing the paper is a job for an adult. (a) False (b) True
39. 39.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
40. 40.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed

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