Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 402 · 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? True or false: the ironing time is kept the same. (a) True (b) False
2. 2.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
4. 4.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
6. 6.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
9. 9.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) writing the message (d) putting the iron away
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a small bowl (d) turmeric powder
11. 11.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
12. 12.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic
13. 13.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) yeast (d) white paper
17. 17.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) writing the message (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) a small bowl (d) a magnet
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a balloon (d) an adult with an iron
20. 20.⚖️ 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 keep it the same (c) we measure it
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) an adult with an iron (d) lemon juice
22. 22.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same cotton bud (c) how dark the writing is (d) the same paper
24. 24.⚖️ 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
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a cotton bud (d) white paper
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
27. 27.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
28. 28.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
29. 29.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
30. 30.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) reading the message
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) an adult with an iron (d) a small bowl
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
34. 34.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
35. 35.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a small bowl (d) a mirror
37. 37.True or false: ironing the paper is a job for an adult. (a) True (b) False
38. 38.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) yeast (d) a magnet

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