Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 292 · 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 steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) plugging in the iron (d) ironing the paper
2. 2.True or false: ironing the paper is a job a child can do. (a) True (b) False
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
4. 4.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
5. 5.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
6. 6.True or false: reading the message is a job a child can do. (a) True (b) False
7. 7.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
8. 8.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
10. 10.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
11. 11.🔮 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
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a magnet (d) an adult with an iron
13. 13.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) writing the message
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) lemon juice (d) a small bowl
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
16. 16.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) yeast (d) a magnet
18. 18.⚖️ 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
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
20. 20.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) letting the paper dry (d) putting the iron away
21. 21.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
22. 22.True or false: putting the iron away is a job for an adult. (a) True (b) False
23. 23.⚖️ 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) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
25. 25.⚖️ 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
26. 26.⚖️ 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) how dark the writing is (c) the kind of juice (d) the iron setting
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a mirror (d) lemon juice
28. 28.True or false: reading the message is a job for an adult. (a) True (b) False
29. 29.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
30. 30.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) yeast (d) white paper
33. 33.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) putting the iron away (d) cutting the lemon
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) lemon juice (d) a mirror
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
36. 36.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
37. 37.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) plugging in the iron (d) cutting the lemon
38. 38.⚖️ 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) how dark the writing is (c) the same paper
39. 39.🛟 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
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a balloon (d) a small bowl

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